Patient Selectable Joint Arthroplasty Devices and Surgical Tools Incorporating Anatomical Relief

ABSTRACT

Disclosed herein are methods, compositions and tools for repairing articular surfaces repair materials and for repairing an articular surface. The articular surface repairs are customizable or highly selectable by patient and geared toward providing optimal fit and function. The surgical tools are designed to be customizable or highly selectable by patient to increase the speed, accuracy and simplicity of performing total or partial arthroplasty.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/491,162 to Wong et al, filed May 27, 2011, andentitled “Patient Selectable Joint Arthroplasty Devices and SurgicalTools Incorporating Anatomical Relief.”

This application further claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/443,155 to Bojarski et al, filed Feb. 15, 2011,and entitled “Patient-Adapted and Improved Articular Implants, Designsand Related Guide Tools.”

Each of the above-described applications are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present disclosure relates to orthopedic methods, systems andprosthetic devices and more particularly relates to methods, systems anddevices for joint replacement and articular resurfacing that incorporateanatomical relief surfaces and/or other features. The present disclosurealso includes surgical tools and/or molds, incorporating anatomicalrelief features that are designed to achieve optimal cut planes in ajoint in preparation for installation of a joint implant.

BACKGROUND OF THE INVENTION

There are various types of cartilage, e.g., hyaline cartilage andfibrocartilage. Hyaline cartilage is found at the articular surfaces ofbones, e.g., in the joints, and is responsible for providing the smoothgliding motion characteristic of moveable joints. Articular cartilage isfirmly attached to the underlying bones and measures typically less than5 mm in thickness in human joints, with considerable variation dependingon joint and site within the joint. In addition, articular cartilage isaneural, avascular, and alymphatic. In adult humans, this cartilagederives its nutrition by a double diffusion system through the synovialmembrane and through the dense matrix of the cartilage to reach thechondrocyte, the cells that are found in the connective tissue ofcartilage.

Adult cartilage has a limited ability of repair; thus, damage tocartilage produced by disease, such as rheumatoid and/or osteoarthritis,or trauma can lead to serious physical deformity and debilitation.Furthermore, as human articular cartilage ages, its tensile propertieschange. The superficial zone of the knee articular cartilage exhibits anincrease in tensile strength up to the third decade of life, after whichit decreases markedly with age as detectable damage to type II collagenoccurs at the articular surface. The deep zone cartilage also exhibits aprogressive decrease in tensile strength with increasing age, althoughcollagen content does not appear to decrease. These observationsindicate that there are changes in mechanical and, hence, structuralorganization of cartilage with aging that, if sufficiently developed,can predispose cartilage to traumatic damage.

For example, the superficial zone of the knee articular cartilageexhibits an increase in tensile strength up to the third decade of life,after which it decreases markedly with age as detectable damage to typeII collagen occurs at the articular surface. The deep zone cartilagealso exhibits a progressive decrease in tensile strength with increasingage, although collagen content does not appear to decrease. Theseobservations indicate that there are changes in mechanical and, hence,structural organization of cartilage with aging that, if sufficientlydeveloped, can predispose cartilage to traumatic damage.

Once damage occurs, joint repair can be addressed through a number ofapproaches. One approach includes the use of matrices, tissue scaffoldsor other carriers implanted with cells (e.g., chondrocytes, chondrocyteprogenitors, stromal cells, mesenchymal stem cells, etc.). Thesesolutions have been described as a potential treatment for cartilage andmeniscal repair or replacement. However, clinical outcomes with biologicreplacement materials such as allograft and autograft systems and tissuescaffolds have been uncertain since most of these materials cannotachieve a morphologic arrangement or structure similar to or identicalto that of normal, disease-free human tissue it is intended to replace.Moreover, the mechanical durability of these biologic replacementmaterials remains uncertain.

Usually, severe damage or loss of cartilage is treated by replacement ofthe joint with a prosthetic material, for example, silicone, e.g. forcosmetic repairs, or metal alloys. See, e.g., U.S. Pat. No. 6,383,228 toSchmotzer, issued May 7, 2002; U.S. Pat. No. 6,203,576 to Afriat et al.,issued Mar. 20, 2001; U.S. Pat. No. 6,126,690 to Ateshian, et al.,issued Oct. 3, 2000. Implantation of these prosthetic devices is usuallyassociated with loss of underlying tissue and bone without recovery ofthe full function allowed by the original cartilage and, with somedevices, serious long-term complications associated with the loss ofsignificant amount of tissue and bone can include infection, osteolysisand also loosening of the implant.

Further, joint arthroplasties are highly invasive and often requiresurgical resection of the entirety or the majority of the articularsurface of one or more bones. With these procedures, the marrow space isoften reamed in order to fit the stem of the prosthesis. The reamingresults in a loss of the patient's bone stock. U.S. Pat. No. 5,593,450to Scott et al. issued Jan. 14, 1997 discloses an oval domed shapedpatella prosthesis. The prosthesis has a femoral component that includestwo condyles as articulating surfaces. The two condyles meet to form asecond trochlear groove and ride on a tibial component that articulateswith respect to the femoral component. A patella component is providedto engage the trochlear groove. U.S. Pat. No. 6,090,144 to Letot et al.issued Jul. 18, 2000 discloses a knee prosthesis that includes a tibialcomponent and a meniscal component that is adapted to be engaged withthe tibial component through an asymmetrical engagement.

Another joint subject to invasive joint procedures is the hip. U.S. Pat.No. 6,262,948 to Storer et al. issued Sep. 30, 2003 discloses a femoralhip prosthesis that replaces the natural femoral head. U.S. PatentPublications 2002/0143402 A1 and 2003/0120347 to Steinberg publishedOct. 3, 2002 and Jun. 26, 2003, respectively, also disclose a hipprosthesis that replaces the femoral head and provides a member forcommunicating with the ball portion of the socket within the hip joint.

A variety of materials can be used in replacing a joint with aprosthetic, for example, silicone, e.g. for cosmetic repairs, orsuitable metal alloys are appropriate. Implantation of these prostheticdevices is usually associated with loss of underlying tissue and boneand, with some devices, serious long-term complications associated withthe loss of significant amounts of tissue and bone can cause looseningof the implant. One such complication is osteolysis. Once the prosthesisbecomes loosened from the joint, regardless of the cause, the prosthesiswill then often be required to be replaced. Since the patient's bonestock is limited, the number of possible replacement surgeries is alsolimited for joint arthroplasty.

As can be appreciated, joint arthroplasties are generally highlyinvasive procedures and can require surgical resection of the entirety,or a majority of, the articular surface of one or more bones involved inthe repair. In many procedures, the marrow space can be fairlyextensively reamed in order to fit the stem of the prosthesis within thebone. Reaming results in a loss of the patient's bone stock and overtime subsequent osteolysis will frequently lead to loosening of theprosthesis. Further, the area where the implant and the bone matedegrades over time requiring the prosthesis to eventually be replaced.Since the patient's bone stock is limited, the number of possiblereplacement surgeries can be limited for joint arthroplasty. In short,over the course of 15 to 20 years, and in some cases even shorter timeperiods, the patient can run out of therapeutic options ultimatelyresulting in a painful, non-functional joint.

In the past, a diseased, injured or defective joint, such as, forexample, a joint exhibiting osteoarthritis, was repaired using standardoff-the-shelf implants and other surgical devices. Specificoff-the-shelf implant designs have been altered over the years toaddress particular issues. For example, several existing designs includeimplant components having rotating parts to enhance joint motion. Rieset al. describes design changes to the distal or posterior condyles of afemoral implant component to enhance axial rotation of the implantcomponent during flexion. See U.S. Pat. Nos. 5,549,688 and 5,824,105.Andriacchi et al. describes a design change to the heights of theposterior condyles to enhance high flexion motion. See also U.S. Pat.No. 6,770,099. However, in altering a design to address a particularissue, historical design changes frequently have created one or moreadditional issues for future designs to address. Collectively, many ofthese issues have arisen from one or more differences between apatient's existing joint anatomy and the corresponding features of animplant component.

Joint implants have historically employed a one-size-fits-all (or afew-sizes-fit-all) approach to implant design. A series of one or more“standard” implant shapes and/or sizes is pre-manufactured andstockpiled, and then one or more of these implants selected forimplantation in the patient. It has been common practice to modify thepatient's anatomical support structures (e.g., cut supporting bonesand/or other structures) to accommodate a chosen implant, and with alimited number of shapes and sizes to of implants choose from, it isvirtually guaranteed that the chosen implant will not be a “perfect fit”to the patient's anatomy. Rather, the chosen implant is likely the “bestfit” or best compromise available, with the surgical procedure stillrequiring removal of significant bone and/or other support tissues toaccommodate the chosen implant size. Accordingly, advanced implantdesigns and related devices and methods that address the needs ofindividual patient's are needed.

Moreover, currently available devices do not optimally provide idealalignment with the articular surfaces and the resultant joint congruity.Poor alignment and poor joint congruity can, for example, lead toinstability of the joint. In the knee joint, instability typicallymanifests as a lateral instability of the joint.

Thus, there remains a need for compositions for joint repair, includingmethods and compositions that facilitate the integration between thecartilage replacement system and the surrounding cartilage. There isalso a need for tools that increase the accuracy of cuts made to thebone in a joint in preparation for surgical implantation of, forexample, an artificial joint.

SUMMARY OF THE INVENTION

The embodiments described herein include advancements in or that ariseout of the area of patient-adapted articular implants that are tailoredto address the needs of individual, single patients. Suchpatient-adapted articular implants offer advantages over the traditionalone-size-fits-all approach, or a few-sizes-fit-all approach. Theadvantages include, for example, better fit, more natural movement ofthe joint, reduction in the amount of bone removed during surgery and aless invasive procedure. Such patient-adapted or patient-specificarticular implants can be created from images of the patient's joint.Based on the images, patient-adapted and/or patient-specific implantcomponents can be selected and/or designed to include features (e.g.,surface contours, curvatures, shapes, widths, lengths, thicknesses, andother features) that match existing features in the single, individualpatient's joint as well as features that approximate an ideal and/orhealthy feature or a combination of patient-adapted or patient-specificand engineered features that may not exist in the patient prior to aprocedure.

Patient-adapted features can include patient-specific and/orpatient-engineered features. Patient-specific (or patient-matched)implant component or guide tool features can include features adapted tomatch one or more of the patient's biological features, for example, oneor more biological/anatomical structures, alignments, kinematics, and/orsoft tissue features. Patient-adapted can include one or moreimplant/tool features that are modified to accommodate various patientanatomical features, or features that are designed or chosen tosubstantially match a patient's anatomical features. Patient-specificcan include surface features that are a substantial negative of,substantially mirror and/or substantially conform to some of all of apatient's native anatomical features. Patient-engineered (orpatient-derived) features of an implant component can be designed and/ormanufactured (e.g., preoperatively designed and manufactured) based onpatient-specific data to substantially enhance or improve one or more ofthe patient's anatomical and/or biological features, Patient-engineeredfeatures can include implants and/or surgical tools having featuresbased on information derived from the patient's anatomy combined withinformation derived from non-patient-specific sources, includinganatomical databases of one or more individuals (including averageddata) from general population groups of similar age, medical condition,age, activity level, ethnicity, geographic location, height, weight,occupation, etc. Patient-engineered features can also include implantsand/or surgical tools having some features based on information derivedfrom the patient's anatomy combined with other features designed orderived from non-patient-specific data, including general engineering orperformance knowledge and/or criteria as well as general biomechanicaldata.

The patient-adapted (e.g., patient-specific and/or patient-engineered)implant components and guide tools described herein can be selected(e.g., from a library), designed (e.g., preoperatively designedincluding, optionally, manufacturing the components, instruments, ortools), and/or selected and designed and/or modified (e.g., by selectinga blank component or tool having certain blank features and thenaltering the blank features to be patient-adapted or patient-specific orpatient-engineered). Moreover, related methods, such as designs andstrategies for resectioning a patient's biological structure also can beselected and/or designed. For example, an implant component bone-facingsurface and a resectioning strategy for the corresponding bone-facingsurface can be selected and/or designed together so that an implantcomponent's bone-facing surface matches the resected surface. Suchresectioning approaches can be performed with saws, blades, burrs,curettes and any other tool known in the art or designed in the future.The resectioning approaches can be implemented using free hand, surgicalnavigation, custom cutting jig or robot assisted approaches. Inaddition, one or more guide tools optionally can be selected and/ordesigned to facilitate the resection cuts that are predetermined inaccordance with resectioning strategy and implant component selectionand/or design.

In various exemplary embodiments, the implants and associated surgicaltools incorporate surface features that can accommodate unusual,unknown, uncertain or distinctive anatomical features in addition toincluding surfaces that conform to corresponding patient-specific and/orsurgically-modified anatomical surfaces of the patient's underlyinganatomical support structures. For example, an implant and/or surgicaltool can include surfaces conforming to patient-specific and/orsurgically-modified anatomical surfaces of the patient's joint, andfurther include a surface opening, void and/or other “anatomical relief”feature that accommodates or avoids one or more osteophytes on thesurface of the targeted anatomical region. In various embodiments, the“anatomical relief” surface of the implant/tool can desirably avoiddirect contact with the unusual/unknown/distinctive feature of theanatomical support structure. In other embodiments, the anatomicalrelief surface can contact or otherwise engage with theunusual/unknown/distinctive surface feature.

In various instances it may be desirous to avoid, eliminate, minimizeand/or reduce implant/tool contact with unusual/unknown/distinctiveanatomical surface features such as osteophytes, voids, soft tissuesand/or other anatomical structures. Avoidance may be desirable becauseof load bearing constraints of the surface feature, imaging difficultiesthat render surface characterizations inaccurate, a desire to allow thefeatures to heal or otherwise remodel, or for many other reasons desiredby the physician and/or implant designers.

In various other instances it may be desirous to increase, enhanceand/or augment implant/tool contact with unusual/distinctive anatomicalsurface features such as osteophytes, voids, soft tissues and/or otheranatomical structures. Enhancement may be desirable because of loadbearing abilities of the surface feature, ability of the feature toincrease securement of the implant/tool against lateral or slidingmovement and/or due to other desires to contact the implant/tool asdesired by the physician and/or implant designers. Enhancement mayfurther be desirable to engage the feature in a manner similar to a“puzzle piece fit” (e.g., the mold or other tool or implant only fitsone way onto the anatomical surface with the feature).

Various embodiments could also incorporate anatomical relief featuresthat correspond to non-surface features of the bone, including featuresbelow the surface of the bone (i.e., subsurface voids or cysts) and/ornon-surface features above the bone (i.e., adjacent and/or surroundingbones, ligaments, tendons, muscles and/or other soft tissues, etc.).

The present disclosure describes novel devices and methods for replacinga portion (e.g., diseased area and/or area slightly larger than thediseased area) of a joint (e.g., cartilage and/or bone) with anon-pliable, non-liquid (e.g., hard) implant material, where the implantand/or surgical tools achieve a near anatomic fit with the surroundingstructures and tissues, and where the implant and/or tool furtherincludes at least one anatomical relief. In cases where the devicesand/or methods include an element associated with the underlyingarticular bone, various embodiments also provide that thebone-associated element achieves a near anatomic alignment with thesubchondral bone. Various embodiments optionally provide for thepreparation of an implantation site with a single cut, or a fewrelatively small cuts.

In various aspects, the anatomical relief can be completely encompassedby the patient-specific or patient-engineered surfaces (i.e., theperiphery of the anatomical relief is completely surrounded bypatient-specific and/or patient-engineered surfaces of theimplant/tool). In other embodiments, the anatomical relief can belocated along one or more edges of an implant/tool's patient-specific orpatient-engineered surfaces, such that at least a portion of a peripheryof the anatomical relief is not bounded by a patient-specific and/orpatient-engineered surface of the implant/tool. The anatomical reliefcan extend inward relative to the implant/tool and/or thepatient-specific or patient-engineered surfaces, can extend outwardrelative to the implant/tool and/or the patient-specific orpatient-engineered surfaces, or can extend both inward and outwardrelative to the implant/tool and/or the patient-specific orpatient-engineered surfaces. In various embodiments the anatomicalrelief can be positioned on an outer or non-bone facing surface of theimplant to accommodate other soft and hard tissues adjacent to theimplant.

Various embodiments disclose a method for providing articularreplacement material, the method comprising the step of producingarticular replacement (e.g., cartilage replacement material) of selecteddimensions (e.g., size, thickness and/or curvature). The method caninclude the steps of (a) measuring the dimensions (e.g., thickness,curvature and/or size) of the intended implantation site or thedimensions of the area surrounding the intended implantation site; and(b) providing cartilage replacement material that conforms to themeasurements obtained in step (a). In certain aspects, step (a)comprises measuring the thickness of the cartilage surrounding theintended implantation site and measuring the curvature of the cartilagesurrounding the intended implantation site. In other embodiments, step(a) comprises measuring the size of the intended implantation site andmeasuring the curvature of the cartilage surrounding the intendedimplantation site. In other embodiments, step (a) comprises measuringthe thickness of the cartilage surrounding the intended implantationsite, measuring the size of the intended implantation site, andmeasuring the curvature of the cartilage surrounding the intendedimplantation site. In other embodiments, step (a) comprisesreconstructing the shape of healthy cartilage surface at the intendedimplantation site.

In any of the methods described herein, one or more components of thearticular replacement material (e.g., the cartilage replacementmaterial) can be non-pliable, non-liquid, solid or hard. The dimensionsof the replacement material can be selected following intraoperativemeasurements. Measurements can also be made using imaging techniquessuch as ultrasound, MRI, CT scan, x-ray imaging obtained with x-ray dyeand fluoroscopic imaging. A mechanical probe (with or without imagingcapabilities) can also be used to select dimensions, for example anultrasound probe, a laser, an optical probe and a deformable material ordevice.

In any of the methods described herein, the replacement material can beselected (for example, from a pre-existing library of repair systems),grown from cells and/or hardened from various materials. Thus, thematerial can be produced pre- or post-operatively. Furthermore, in anyof the methods described herein the repair material can also be shaped(e.g., manually, automatically or by machine), for example usingmechanical abrasion, laser ablation, radiofrequency ablation,cryoablation and/or enzymatic digestion.

In any of the methods described herein, the articular replacementmaterial can comprise synthetic materials (e.g., metals, liquid metals,polymers, alloys or combinations thereof) or biological materials suchas stem cells, fetal cells or chondrocyte cells.

In a still further aspect, various embodiments describe a partial orfull articular prosthesis comprising a first component comprising acartilage replacement material; and an optional second componentcomprising one or more metals, wherein said second component can have acurvature similar to subchondral bone, wherein said prosthesis comprisesless than about 80% of the articular surface. In certain embodiments,the first and/or second component comprises a non-pliable material(e.g., a metal, a polymer, a metal alloy, a solid biological material).Other materials that can be included in the first and/or secondcomponents include polymers, biological materials, metals, metal alloysor combinations thereof. Furthermore, one or both components can besmooth or porous (or porous coated) using any methods or mechanisms toachieve in-growth of bone known in the art. In certain embodiments, thefirst component exhibits biomechanical properties (e.g., elasticity,resistance to axial loading or shear forces) similar to articularcartilage. The first and/or second component can be bioresorbable and,in addition, the first or second components can be adapted to receiveinjections.

In another aspect, an articular prosthesis comprising an externalsurface located in the load bearing area of an articular surface,wherein the dimensions of said external surface achieve a near anatomicfit with the adjacent, underlying or opposing cartilage is provided. Theprosthesis can comprise one or more metals or metal alloys.

In a still further embodiment, a partial articular prosthesis comprising(a) a metal or metal alloy; and (b) an external surface located in theload bearing area of an articular surface, wherein the external surfacedesigned to achieve a near anatomic fit with the adjacent surrounding,underlying or opposing cartilage is provided.

Any of the repair systems or prostheses described herein (e.g., theexternal surface) can comprise a polymeric material, for exampleattached to said metal or metal alloy. Any of the repair systems can beentirely composed of polymer. Further, any of the systems or prosthesesdescribed herein can be adapted to receive injections, for example,through an opening in the external surface of said cartilage replacementmaterial (e.g., an opening in the external surface terminates in aplurality of openings on the bone surface). Bone cement, polymers,Liquid Metal, therapeutics, and/or other bioactive substances can beinjected through the opening(s). In certain embodiments, bone cement isinjected under pressure in order to achieve permeation of portions ofthe marrow space with bone cement. In addition, any of the repairsystems or prostheses described herein can be anchored in bone marrow orin the subchondral bone itself. One or more anchoring extensions (e.g.,pegs, pins, etc.) can extend through the bone and/or bone marrow.

In another aspect, a method of designing an articular implant comprisingthe steps of obtaining an image of a joint, wherein the image includesboth normal cartilage and diseased cartilage; reconstructing dimensionsof the diseased cartilage surface to correspond to normal cartilage; anddesigning the articular implant to match the dimensions of thereconstructed diseased cartilage surface or to match an area slightlygreater than the diseased cartilage surface is provided. The image canbe, for example, an intraoperative image including a surface detectionmethod using any techniques known in the art, e.g., mechanical, optical,ultrasound, and known devices such as MRI, CT, ultrasound, digitaltomosynthesis and/or optical coherence tomography images. In certainembodiments, reconstruction is performed by obtaining a surface thatfollows the contour of the normal cartilage. The surface can beparametric and include control points that extend the contour of thenormal cartilage to the diseased cartilage and/or a B-spline surface. Inother embodiments, the reconstruction is performed by obtaining a binaryimage of cartilage by extracting cartilage from the image, whereindiseased cartilage appears as indentations in the binary image; andperforming, for example, a morphological closing operation (e.g.,performed in two or three dimensions using a structuring element and/ora dilation operation followed by an erosion operation) to determine theshape of an implant to fill the areas of diseased cartilage.

In yet another aspect, described herein are systems for evaluating thefit of an articular repair system into a joint, the systems comprisingone or more computing means capable of superimposing a three-dimensional(e.g., three-dimensional representations of at least one articularstructure and of the articular repair system) or a two-dimensionalcross-sectional image (e.g., cross-sectional images reconstructed inmultiple planes) of a joint and an image of an articular repair systemto determine the fit of the articular repair system. The computing meanscan be: capable of merging the images of the joint and the articularrepair system into a common coordinate system; capable of selecting anarticular repair system having the best fit; capable of rotating ormoving the images with respect to each other; and/or capable ofhighlighting areas of poor alignment between the articular repair systemand the surrounding articular surfaces. The three-dimensionalrepresentations can be generated using a parametric surfacerepresentation.

In yet another aspect, surgical tools for preparing a joint to receivean implant are described, for example a tool comprising one or moresurfaces or members that conform at least partially to the shape of thearticular surfaces of the joint (e.g., a femoral condyle and/or tibialplateau of a knee joint). In certain embodiments, the tool comprisesLucite silastic and/or other polymers or suitable materials. The toolcan be re-useable or single-use. The tool can be comprised of a singlecomponent or multiple components. In certain embodiments, the toolcomprises an array of adjustable, closely spaced pins. In anyembodiments described herein, the surgical tool can be designed tofurther comprise an aperture therein, for example one or more apertureshaving dimensions (e.g., diameter, depth, etc.) smaller or equal to oneor more dimensions of the implant and/or one or more apertures adaptedto receive one or more injectables. Any of the tools described hereincan further include one or more curable (hardening) materials orcompositions, for example that are injected through one or moreapertures in the tool and which solidify to form an impression of thearticular surface.

In still another aspect, a method of evaluating the fit of an articularrepair system into a joint is described herein, the method comprisingobtaining one or more three-dimensional images (e.g., three-dimensionalrepresentations of at least one articular structure and of the articularrepair system) or two-dimensional cross-sectional images (e.g.,cross-sectional images reconstructed in multiple planes) of a joint,wherein the joint includes at least one defect or diseased area;obtaining one or more images of one or more articular repair systemsdesigned to repair the defect or diseased area; and evaluating theimages to determine the articular repair system that best fits thedefect (e.g., by superimposing the images to determine the fit of thearticular repair system into the joint). In certain embodiments, theimages of the joint and the articular repair system are merged into acommon coordinate system. The three-dimensional representations can begenerated using a parametric surface representation. In any of thesemethods, the evaluation can be performed by manual visual inspectionand/or by computer (e.g., automated). The images can be obtained, forexample, using a C-arm system and/or radiographic contrast.

The present disclosure also describes tools. In accordance with variousembodiments, a surgical tool includes a template. The template has atleast one contact surface for engaging a surface associated with ajoint. The at least one contact surface substantially conforms with thesurface and, optionally, incorporates a least one anatomical reliefsurface or other feature. The template further includes at least oneguide aperture for directing movement of a surgical instrument.

In accordance with related embodiments, the surface may be an articularsurface, a non-articular surface, a cartilage surface, a weight bearingsurface, a non-weight surface and/or a bone surface. The joint has ajoint space, with the surface either within the joint space or externalto the joint space. The template may include a mold. The template mayinclude at least two pieces, the at least two pieces including a firstpiece that includes one or more of the at least one contact surfaces,the second piece including one or more of the at least one guideapertures or guide surfaces. The at least one contact surface mayinclude a plurality of discrete contact surfaces, optionally includingat least one anatomical relief surface or other feature. In otherembodiments the at least one contact surface may include a pluralityanatomical relief surfaces or other features.

In accordance with further embodiments, the contact surface may be madeof a biocompatible material, such as acylonitrile butadiene styrene,polyphenylsulfone, and polycarbonate. The contact surface may be capableof heat sterilization without deforming. For example, the contactsurface may be capable of heat sterilization without deforming attemperatures lower than 207 degrees Celsius, such as a contact surfacemade of polyphenylsulfone. The contact surface may be substantiallytransparent or semi-transparent, such as a contact surface made of Somos11120.

In still further embodiments, the template may include a referenceelement, such as a pin or aiming device, for establishing a referenceplane relative to at least one of a biomechanical axis and an anatomicalaxis of a limb. In other embodiments, the reference element may be usedfor establishing an axis to assist in correcting an axis deformity.

In various embodiments, the joint surface is at least one of anarticular surface, a non-articular surface, a cartilage surface, aweight bearing surface, a non-weight bearing surface, and a bonesurface. The joint has a joint space, wherein the surface may be withinthe joint space or external to the joint space. The at least one contactsurface may include a plurality of discrete contact surfaces. Creatingthe template may include rapid prototyping, milling and/or creating amold, the template furthermore may be sterilizable and/or biocompatible.The rapid prototyping may include laying down successive layers ofplastic. The template may be a multi-piece template. The multi-piecetemplate may include a first piece that includes one or more of the atleast one contact surfaces, and a second piece that includes one or moreof the at least one guide apertures or guide surface or element.Obtaining the image may include determining dimensions of boneunderlying the cartilage, and adding a predefined thickness to the bonedimensions, the predefined thickness representing the cartilagethickness. Adding the predefined thickness may be a function of at leastone of an anatomic reference database, an age, a gender, and racematching. Obtaining the imaging may include performing an opticalimaging technique, an ultrasound, a CT, a spiral CT, and/or an MRI.

In accordance with another embodiment, a surgical tool includes atemplate. The template has at least one contact surface for engaging asurface associated with a joint, the at least one contact surfacesubstantially conforming with the surface and, optionally, at least oneanatomical relief surface or other feature. The contact surface isoptionally substantially transparent or semi-transparent. The templatefurther includes at least one guide aperture for directing movement of asurgical instrument.

In accordance with another embodiment, a method of joint arthroplasty ispresented. The method includes obtaining an image associated with ajoint. A template is created having at least one contact surface thatconforms with a surface associated with the joint as well as,optionally, at least one anatomical relief surface of other feature, thetemplate including a reference element and at least one guide apertureor guide surface or element for directing movement of a surgicalinstrument. The template is aligned in an orientation on the joint suchthat the reference element establishes a reference plane relative to abiomechanical axis of a limb. The template is anchored to the joint suchthat the contact surface abuts the joint in said orientation. Thebiomechanical axis may extend, for example, from a center of a hip to acenter of an ankle. A surgical tool is aligned using the referenceelement to correct an axis deformity.

In accordance with another embodiment, a surgical tool includes atemplate. The template includes a mold having at least one contactsurface for engaging a surface associated with a joint and, optionally,at least one anatomical relief surface or other feature. The at leastone contact surface substantially conforms with the surface. The mold ismade of a biocompatible material. The template further includes at leastone guide aperture or guide surface or guide element for directingmovement of a surgical instrument. The mold may be sterilizable and/orsubstantially transparent or semi-transparent.

In accordance with other embodiments, methods of using a surgical toolare presented. The surgical tool includes a first template removablyattached to a second template. The method includes anchoring the firsttemplate to a femoral joint surface, the first template having a firstcontact surface for engaging the femoral joint surface and, optionally,at least one anatomical relief surface or other feature. The secondtemplate is anchored to a tibial joint surface, the second templatehaving a second contact surface for engaging a tibial joint surface.After anchoring the first template and the second template, the secondtemplate is released from the first template, such that the secondtemplate is capable of moving independent of the first template.

In accordance with related embodiments, the disclosed methods mayfurther include using the second template to direct a surgical cut onthe tibia. Anchoring the second template may occur subsequent or priorto anchoring the first template. At least one of the first and secondtemplates may include a mold. The first contact surface maysubstantially conform with the femoral joint surface and includeoptionally at least one anatomical relief surface or other feature. Thesecond contact surface may substantially conform with the tibial jointsurface.

In accordance with another embodiment, a method of performing jointarthroplasty includes obtaining a computer image of a surface associatedwith a first joint. At least one deformity or other surface feature seenin the computer image can be modified, enhanced, increased, decreaseand/or reshaped. The at least one deformity or other surface feature isused, at least in part, to create a template. The template includes atleast one contact surface for engaging the surface, with optionally atleast one anatomical relief surface of other feature for engaging,avoiding and/or encompassing the surface feature, the at least onecontact surface substantially conforming with the surface.

In accordance with another embodiment, a method of performing jointarthroplasty includes obtaining a computer image of a surface associatedwith a first joint. At least one deformity seen in the computer image isremoved such as a biomechanical or anatomical axis deformity, so as toform an improved anatomic or functional result. The at least onedeformity is removed in the surgical planning by modifying the shape orposition of a template including the shape and/or position of guideapertures, guide surface or guide elements. A template is providedbased, at least in part, on the removal of the deformity. The templateincludes at least one contact surface for engaging the joint surface aswell as optionally at least one anatomical relief surface of otherfeature for engaging and/or encompassing at least one surface feature ofthe joint. The shape and/or position of guide apertures, guide surfaceor guide elements is selected or designed to achieve a correction of thedeformity.

In accordance with related embodiments, the template may be used in asurgical procedure. The template may include at least one guideaperture, guide surface or guide elements, the method further includingusing the at least one guide aperture, guide surface or guide elementsto direct movement of a surgical instrument. The at least one surfacefeature may include a osteophyte, a subchondral cyst, and/or anarthritic deformation.

In accordance with another embodiment, a method of performing jointarthroplasty includes obtaining an image of a surface associated with afirst joint, the image including at least two surface features. Atemplate is provided, based at least in part on the image, the templatehaving at least one contact surface for engaging portions of the surfacefree of one of the surface features (such as, for example, where thesurface feature has been removed or modified surgically), while thetemplate has optionally at least one anatomical relief surface or otherfeature for accommodating at least the other surface feature. The atleast one contact surface substantially conforms with the portions ofthe surface. The template is used in a surgical procedure.

In accordance with related embodiments, the template may include atleast one guide aperture, guide surface or guide elements, the methodfurther including using the at least one guide aperture, guide surfaceor guide elements to direct movement of a surgical instrument. The atleast one surface feature and/or deformity may include a osteophyte, asubchondral cyst, and/or an arthritic deformation.

In accordance with another embodiment, a method of performing jointarthroplasty includes providing a template. The template is fixated tobone associated with a joint without performing any cuts to the joint.The template may be used in a surgical procedure.

In accordance with another embodiment, a system for joint arthroplastyincludes a first template. The first template includes at least onesurface for engaging a first surface of a joint as well as optionally atleast one anatomical relief surface or other feature, the at least onesurface being a mirror and/or negative image of portions or all of thefirst surface. The first template further includes at least one guidefor directing movement of a surgical instrument. A linkagecross-references at least one surgical tool relative to said guide andrelative to one of an anatomical and a biomechanical axis.

In accordance with related embodiments, the surgical tool may be asecond template, the second template including at least one guide fordirecting movement of a surgical instrument. The second template mayinclude a surface that is a mirror and/or negative image of a secondsurface of the joint. The second joint surface may oppose the firstjoint surface. At least one guide of the second template may direct thesurgical instrument in at least one of a cut, a milling, and a drillingoriented in a predefined location relative to said first template andadapted in shape, size or orientation to an implant shape. The shapeand/or position of the at least one guide of the first template may bebased, at least in part, on one or more axis related to said joint. Thelinkage may be an attachment mechanism, which may cause the firsttemplate to directly contact the at least one surgical tool, oralternatively, attaches the first template and the at least one surgicaltool such that the first template and the at least one surgical tool donot directly contact each other. The linkage may allow for rotationrelative to one of an anatomical and a biomechanical axis. The firsttemplate may include a removably attached block, the block including theat least one guide of the first template.

In accordance with another embodiment, a system for joint arthroplastyis presented that includes a first template. The first template includesat least one first template surface for engaging a first surface of ajoint and optionally at least one anatomical relief surface or otherfeature, the first template surface being a mirror and/or negative imageof portions or all of the first surface. The first template furtherincludes at least one guide for directing movement of a surgicalinstrument. A second template includes at least one second templatesurface for engaging a second surface of a joint, the second templatebeing a mirror and/or negative image of portions or all of the secondsurface. The second template further includes at least one guide fordirecting movement of a surgical instrument. A linkage cross-referencesthe first template and the second template. The linkage may optionallyallow for rotation relative to one of an anatomical and a biomechanicalaxis.

In accordance with related embodiments, the at least one contact surfaceof the first template is substantially a mirror and/or negative image ofthe first surface. The method may further include obtaining electronicimage data of the joint, and determining a shape of the at least onecontact surface of the first template based, at least in part, onelectronic image data. In accordance with other related embodiments, themethod may further include, prior to directing movement of the surgicalinstrument, positioning at least one contact surface of the secondtemplate to the second joint surface. The at least one contact surfaceof the second template may be substantially a mirror and/or negativeimage of the second surface. The method may further include obtainingelectronic image data of the joint, and determining a shape of the atleast one contact surface of the second template based, at least inpart, on electronic image data.

In accordance with yet further related embodiments, cross-referencingthe second template to the first template may includes attaching thesecond template to the first template. Attaching the second template tothe first template may include performing intraoperative adjustments.The second template is attached to the first template via a pin, andwherein performing intraoperative adjustments includes rotating thesecond template around the pin. The method may further includeperforming an intraoperative adjustment on the position of the secondtemplate on the second surface of the joint, wherein performing theintraoperative adjustment includes using one of spacers, ratchets, andtelescoping devices. The method may further include performing anintraoperative adjustment on the position of the second template on thesecond surface of the joint, wherein performing the intraoperativeadjustment includes adjusting for at least one of joint flexion, jointextension, joint abduction, and joint rotation. Directing movement ofthe surgical instrument using the at least one guide of the secondtemplate may include making one or more cuts or drill holes, the methodfurther comprising implanting a joint prosthesis as a function of theone or more cuts or drill holes. The first template may include at leastone guide, the method further comprising directing movement of asurgical instrument using the at least one guide of the first template.Directing movement of the surgical instrument using the at least oneguide of the first template may include making one or more cuts or drillholes, the method further comprising implanting a joint prosthesis as afunction of the one or more cuts or drill holes. Directing movement ofthe surgical instrument using the at least one guide of the secondtemplate may include making at least one of a cut, a drill hole, and areaming, the method further comprising implanting a joint prosthesis.

In still further embodiments, the first surface of the joint may be afemoral surface, and the second surface of the joint may be a tibialsurface. The method may further include obtaining electronic image dataof a joint, determining the at least one of a biomechanical axis and ananatomical axis of the joint based, at least in part, on the electronicimage data, wherein the shape and/or position of the guide of the secondtemplate is based, at least in part, on the at least one of thebiomechanical axis and the anatomical axis. The electronic image datamay be obtained pre-operatively, intraoperatively, optically, an MRI, aCT, and/or a spiral CT. The first template may include a thicknessbased, at least in part, on at least one of a thickness of an implant tobe attached to the first surface of the joint and a desired spacebetween two opposing surfaces of the joint.

In accordance with another embodiment, a method of joint arthroplastyincludes positioning at least one contact surface of a first templateonto a first surface of a joint and, optionally, at least one anatomicalrelief surface of other feature to encompass, avoid and/or engage atleast a portion of a surface feature of the joint, wherein the at leastone contact surface of the first template is substantially a mirrorand/or negative image of the first surface. A second template iscross-referenced to the first template to align position of the secondtemplate onto a second surface of the joint, the at least one contactsurface of the second template substantially a mirror and/or negativeimage of the second surface of the joint. The second template includesat least one guide. Movement of the surgical instrument is directedusing the at least one guide of the second template.

In accordance with another embodiment, a method of joint arthroplastyincludes positioning at least one contact surface of a first templateonto a first surface of a joint and, optionally, at least one anatomicalrelief surface or other feature to encompass, avoid and/or engage atleast a portion of a surface feature of the joint. A second template iscross-referenced to the first template to align position of the secondtemplate on a second surface of the joint, the second template includingat least one guide. Cross-referencing allows rotation of the secondtemplate relative to one of a biomechanical and an anatomical axis.Movement of the surgical instrument is directed using the at least oneguide of the second template.

In accordance with another embodiment, the template may include at leastone surface for engaging a surface of a joint and, optionally, at leastone anatomical relief surface or other feature to encompass, avoidand/or engage at least a portion of a surface feature of the joint, thesurface being a mirror and/or negative image of portions or all of thesurface. Obtaining electronic image data may include at least one of aCT scan, MRI scan, optical scan, and a ultrasound imaging. Obtainingelectronic image data may include obtaining image data of a medialspace, a lateral space, an anterior space, and/or a posterior space ofthe joint. At least two of the lateral space, anterior space, andposterior space of the joint may be compared. Obtaining image data maybe performed in two dimensions or three dimensions. Determining width ofthe joint may include measuring the distance from the subchondral boneplate of one articular surface to the subchondral bone plate of theopposing articular surface. Alternatively, determining width of thejoint may include measuring the distance from the subchondral bone plateof one articular surface to the subchondral bone plate of the opposingarticular surface. Obtaining the image data of the joint may beperformed in at least one of joint flexion, joint extension, and jointrotation. At least one of the shape and position of the guide may befurther based, at least in part, on the anatomical or biomechanical axisalignment of the joint.

In accordance with related embodiments, the method may further includemeasuring at least one axis associated with the joint. Measuring mayinclude a standing x-ray, a weight bearing x-ray, a CT scout scan, a MRIlocalizer scan, a CT scan, and/or a MRI scan. The axis may include aplurality of axis measurements, plurality of planes, or a combination ofan axis and a plane. Obtaining image data may include a spiral CT,spiral CT arthography, MRI, optical imaging, optical coherencetomography, and/or ultrasound. The template may include at least onecontact surface for engaging a surface of the joint and optionally atleast one anatomical relief surface or other feature to encompass, avoidand/or engage at least a portion of a surface feature of the joint, thecontact surface being a mirror and/or negative image of portions or allof the joint surface.

In accordance with another embodiment, a surgical tool includes atemplate having a surface for engaging a joint surface and optionally atleast one anatomical relief surface or other feature to encompass, avoidand/or engage at least a portion of a surface feature of the joint, thesurface being a mirror and/or negative image of a portion or all of thejoint surface. The template further includes two or more guides fordirecting movement of a surgical instrument, wherein the shape and/orposition of at least one of the guides is based, at least in part, on atleast one axis related to said joint.

In accordance with related embodiments, the template further includes ablock removably attached to the surface, the block including the two ormore guides. The two or more guides may include at least one guide for acut, a milling, and a drilling. A second surgical tool may be attachedto the template, the second tool including at least one guide aperturefor guiding a surgical instrument. At least one guide of the secondsurgical tool may guide a surgical instrument to make cuts that areparallel, non-parallel, perpendicular, or non-perpendicular to cutsguided by the first template.

In accordance with another embodiment, a method for joint arthroplastyincludes performing a first cut on a joint to create a first cut jointsurface. Performing the first cut includes positioning at least onecontact surface of a first template onto a first surface of a joint andoptionally at least one anatomical relief surface or other feature toencompass, avoid and/or engage at least a portion of a surface featureof the joint, the at least one contact surface being a mirror and/ornegative image of the first surface of the joint. The first templateincludes a guide for directing movement of a surgical instrument toperform the first cut. The first cut is cross-referenced to perform asecond cut associated with an opposing surface of the joint.

In accordance with related embodiments, cross-referencing the first cutto make the second cut may include attaching a second template to thefirst template so as to assist positioning at least one contact surfaceof the second template onto a second surface of the joint. The secondtemplate includes a guide for directing movement of a surgicalinstrument to perform the second cut. The second template may include atleast one contact surface being a mirror and/or negative image of thesecond surface of the joint. Cross-referencing the first cut to make thesecond cut may include positioning at least one contact surface of athird template onto at least a portion of the first cut surface, andattaching a second template to the third template so as to position atleast one contact surface of the second template onto a second surfaceof the joint. The at least one contact surface of the third template maybe a mirror and/or negative image of the first cut surface. The firstcut may be a horizontal femoral cut, with the second cut being avertical femoral cut. The first cut may be femoral cut with the secondcut being a tibial cut. The first cut may be a femoral cut, and thesecond cut is a patellar cut. The first cut may be an acetabular reamingand the second cut is a femoral cut.

In accordance with another embodiment, a method for joint arthroplastyincludes positioning at least one contact surface of a template onto asurface of a joint and optionally at least one anatomical relief surfaceor other feature to encompass, avoid and/or engage at least a portion ofa surface feature of the joint, the at least one contact surface being amirror and/or negative image of at least a portion of the surface of thejoint. The template includes a guide for directing movement of asurgical instrument. The first template is stabilized onto the firstsurface.

In accordance with related embodiments, the method may further includeobtaining electronic image data of the joint, and determining a shape ofthe at least one contact surface of the first template based, at leastin part, on electronic image data, and optionally determining a shape ofthe at least one anatomical relief surface or other feature, at least inpart, on electronic image data of the surface feature of the joint (oran estimated area of imaging uncertainty). Stabilizing may include usingk-wires, a screw, an anchor, and/or a drill bit left in place on thejoint. Stabilizing may includes positioning the contact surface and/oranatomical relief surface(s) on at least one or more concavities andconvexities on the joint. Stabilizing may include positioning thecontact surface on at least one concavity and at least convexity on thejoint. Stabilizing may include positioning the contact surface, at leastpartially, on an arthritic portion of the joint. Stabilizing may includepositioning the contact surface, at least partially, on an interfacebetween a normal and an arthritic portion of the joint. Stabilizing mayinclude positioning the contact surface, at least partially, against ananatomic feature. The anatomic feature may be a trochlea, anintercondylar notch, a medial condyle and a lateral condyle, a medialtrochlea and a lateral trochlea, a medial tibial plateau and a lateraltibial plateau, a fovea capities, an acetabular fossa, a tri-radiatecartilage, an acetabular wall, or an acetabular rim. Positioning thecontact surface on the surface of the joint may include positioning thecontact surface on, at least partially, a normal portion of the joint.Positioning the at least one anatomical relief surface or other featureon the surface feature of the joint may include encompassing and/orengaging at least a portion of a surface feature of the joint.Determining the position of the guide on the template may be based, atleast in part, on ligament balancing and/or to optimize at least one offlexion and extension gap. The method may further include adjusting theposition of the guide relative to the joint intraoperatively, using forexample, a spacer, a ratchet device, and a pin that allows rotation.

In accordance with another embodiment, a method for joint arthroplastyincludes positioning at least one contact surface of a template onto asurface of a joint and optionally at least one anatomical relief surfaceor other feature to encompass, avoid and/or engage at least a portion ofa surface feature of the joint, such that the contact surface, at leastpartially, rests on, and is a mirror and/or negative image of, aninterface between an arthritic and a normal portion of the jointsurface. The template includes a guide for directing movement of asurgical instrument. A surgical intervention is made on the joint withthe surgical instrument based, at least in part, on the guide.

In accordance with another embodiment, a template includes at least onecontact surface for positioning onto a surface of a joint and optionallyat least one anatomical relief surface or other feature to encompass,avoid and/or engage at least a portion of a surface feature of thejoint, the contact surface at least partially being a mirror and/ornegative image of an interface between an arthritic and a normal portionof the joint surface. A guide directs movement of a surgical instrument.

In accordance with another embodiment, a method for joint arthroplastyincludes providing a template that includes at least one surface forengaging a surface of a joint and, optionally, at least one anatomicalrelief surface or other feature to encompass, avoid and/or engage atleast a portion of a surface feature of the joint based, at least inpart, on substantially isotropic input data. The surface is a mirrorand/or negative image of portions or all of the joint surface. Thetemplate includes at least one guide for directing movement of asurgical instrument.

In accordance with another embodiment, a method for ligament repairincludes obtaining electronic image data of at least one surfaceassociated with a ligament. A first template is created based, at leastin part, on the image data. The first template has at least one contactsurface that conforms with at least a portion of the surface and,optionally, at least one anatomical relief surface of other feature toaccommodate the ligament. The first template includes at least one guidefor directing movement of a surgical instrument involved with theligament repair.

In related embodiments, the ligament may be an anterior cruciateligament or a posterior cruciate ligament. The method may furtherinclude determining a tunnel site for a ligament graft. Determining thetunnel site may include identifying an origin of the ligament on a firstarticular surface, and an insertion position onto a second articularsurface opposing the first articular surface. Determining the tunnelsite may include identifying at least one of a bony landmark and aremainder of a ligament based on the image data. The surface oranatomical relief surface may be adjacent to the tunnel site, or anon-weight bearing surface. The first template may includes a drillguide aperture, the method further including positioning the templatesuch that the at least one contact surface contacts the at least aportion of the surface and, optionally, at least one anatomical reliefsurface of other feature encompasses, avoids and/or engages at least aportion of a surface feature of the joint, and drilling a ligamenttunnel, wherein the drilling is guided by the drill guide aperture. Atleast one of the shape, position and orientation of the drill guideaperture on the first template may be based, at least in part, on adistance of the tunnel to adjacent cortical bone. The drill guideaperture may includes a stop, such that a desired drill depth isobtained. The image data may be obtained preoperatively. The image datamay be obtained by a CT scan or an MRI scan. The image data may beobtained in joint flexion, joint extension, joint abduction, jointadduction, and/or joint rotation. The method may further includeidentifying a graft harvest site based on the image data, and using thefirst template to guide harvesting of at least one of ligament and boneform the graft harvest site. The method may further includecross-referencing a second template to the first template to alignposition of the second template on a second surface associated with theligament, the second template including at least one guide, anddirecting movement of the instrument using the at least one guide of thesecond template relative to said guide. The first and second surfacesmay be opposing articular surfaces. The first surface may be a femoralsurface and the second surface may be a tibial surface. The firsttemplate may include a tissue retractor. The tissue retractor may be aflange or an extender on the template. The template may be used forsingle bundle or a double bundle ligament reconstruction.

In any of the embodiments and aspects described herein, the joint canbe, without limitation, a knee, shoulder, hip, vertebrae, elbow, ankle,foot, toe, hand, wrist or finger.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features disclosed herein will be more readily understoodby reference to the following detailed description, taken with referenceto the accompanying drawings, in which:

FIG. 1 is a flowchart depicting various disclosed methods including,measuring the size of an area of diseased cartilage or cartilage loss,measuring the thickness of the adjacent cartilage, and measuring thecurvature of the articular surface and/or subchondral bone. Based onthis information, a best-fitting implant can be selected from a libraryof implants or a patient specific custom implant can be generated. Theimplantation site is subsequently prepared and the implantation isperformed.

FIGS. 2 A-H illustrate, in cross-section, various stages of kneeresurfacing, in accordance with various embodiments disclosed herein.FIG. 2 A shows an example of normal thickness cartilage and a cartilagedefect. FIG. 2 B shows an imaging technique or a mechanical, optical,laser or ultrasound device measuring the thickness and detecting asudden change in thickness indicating the margins of a cartilage defect.FIG. 2 C shows a weight-bearing surface mapped onto the articularcartilage. FIG. 2 D shows an intended implantation site and cartilagedefect. FIG. 2 E depicts placement of an exemplary single componentarticular surface repair system. FIG. 2 F shows an exemplarymulti-component articular surface repair system. FIG. 2 G shows anexemplary single component articular surface repair system. FIG. 2 Hshows an exemplary multi-component articular surface repair system.

FIGS. 3 A-E, illustrate, in cross-section, exemplary knee imaging andresurfacing, in accordance with various embodiments. FIG. 3 A shows amagnified view of an area of diseased cartilage. FIG. 3 B shows ameasurement of cartilage thickness adjacent to the defect. FIG. 3 Cdepicts placement of a multi-component mini-prosthesis for articularresurfacing. FIG. 3 D is a schematic depicting placement of a singlecomponent mini-prosthesis utilizing stems or pegs. FIG. 3 E depictsplacement of a single component mini-prosthesis utilizing stems and anopening for injection of bone cement.

FIGS. 4 A-C, illustrate, in cross-section, other exemplary kneeresurfacing devices and methods, in accordance with various embodiments.FIG. 4 A depicts normal thickness cartilage in the anterior and centraland posterior portion of a femoral condyle and a large area of diseasedcartilage in the posterior portion of the femoral condyle. FIG. 4 Bdepicts placement of a single component articular surface repair system.FIG. 4 C depicts a multi-component articular surface repair system.

FIGS. 5 A-B show single and multiple component devices, in accordancewith various embodiments. FIG. 5A shows an exemplary single componentarticular surface repair system with varying curvature and radii. FIG. 5B depicts a multi-component articular surface repair system with asecond component that mirror and/or negatives the shape of thesubchondral bone and a first component closely matches the shape andcurvature of the surrounding normal cartilage.

FIGS. 6 A-B show exemplary articular repair systems having an outercontour matching the surrounding normal cartilage, in accordance withvarious embodiments disclosed herein. The systems are implanted into theunderlying bone using one or more pegs.

FIG. 7 shows a perspective view of an exemplary articular repair deviceincluding a flat surface to control depth and prevent toggle; anexterior surface having the contour of normal cartilage; flanges toprevent rotation and control toggle; a groove to facilitate tissuein-growth, in accordance with one embodiment.

FIGS. 8 A-D depict, in cross-section, another example of an implant withmultiple anchoring pegs, in accordance with various embodiments. FIG. 8B-D show various cross-sectional representations of the pegs: FIG. 8 Bshows a peg having a groove; FIG. 8 C shows a peg withradially-extending arms that help anchor the device in the underlyingbone; and FIG. 8 D shows a peg with multiple grooves or flanges.

FIG. 9 A-B depict an external view of an exemplary implant with multipleanchoring pegs and depict how the pegs are not necessarily linearlyaligned along the longitudinal axis of the device, in accordance withvarious embodiments.

FIGS. 10 A-E depict an exemplary implant having radially extending arms,in accordance with various embodiments. FIGS. 10 B-E are overhead viewsof the implant showing that the shape of the peg need not be conical.

FIG. 11 A illustrates a femur, tibia and fibula along with themechanical and anatomic axes. FIGS. 11 B-E illustrate the tibia with theanatomic and mechanical axis used to create a cutting plane along with acut femur and tibia. FIG. 11 F illustrates the proximal end of the femurincluding the head of the femur.

FIG. 12 shows an example of a surgical tool having one surface matchingthe geometry of an articular surface of the joint, in accordance withone embodiment. Also shown is an aperture in the tool capable ofcontrolling drill depth and width of the hole and allowing implantationof an insertion of implant having a press-fit design.

FIG. 13 is a flow chart depicting various methods described and used tocreate a mold for preparing a patient's joint for arthroscopic surgery,in accordance with one embodiment.

FIG. 14 A depicts, in cross-section, an example of a surgical toolcontaining an aperture through which a surgical drill or saw can fit, inaccordance with one embodiment. The aperture guides the drill or saw tomake the proper hole or cut in the underlying bone. Dotted linesrepresent where the cut corresponding to the aperture will be made inbone.

FIG. 14 B depicts, in cross-section, an example of a surgical toolcontaining apertures through which a surgical drill or saw can fit andwhich guide the drill or saw to make cuts or holes in the bone, inaccordance with one embodiment. Dotted lines represent where the cutscorresponding to the apertures will be made in bone.

FIGS. 15 A-R illustrate tibial cutting blocks and molds used to create asurface perpendicular to the anatomic axis for receiving the tibialportion of a knee implant, in accordance with various embodiments.

FIGS. 16 A-O illustrate femur cutting blocks and molds used to create asurface for receiving the femoral portion of a knee implant, inaccordance with various embodiments. FIG. 16 P illustrates an axisdefined by the center of the tibial plateau and the center of the distaltibia. FIG. 16 q shows an axis defining the center of the tibial plateauto the femoral head. FIGS. 16 R and 16 S show isometric views of afemoral template and a tibial template, respectively. FIG. 16 Tillustrates a femoral guide reference tool attached to the femoraltemplate. FIG. 16 U illustrates a sample implant template positioned onthe condyle. FIG. 16 V is an isometric view of the interior surface ofthe sample implant template. FIG. 16 W is an isometric view of thetibial template attached to the sample implant. FIG. 16 X shows a tibialtemplate that may be used, after the tibial cut has been made, tofurther guide surgical tools. FIG. 16 Y shows a tibial implant andfemoral implant inserted onto the tibia and femur, respectively.

FIG. 17 A-G illustrate patellar cutting blocks and molds used to preparethe patella for receiving a portion of a knee implant.

FIG. 18 A-H illustrate femoral head cutting blocks and molds used tocreate a surface for receiving the femoral portion of a knee implant.

FIG. 19 A-D illustrate acetabulum cutting blocks and molds used tocreate a surface for a hip implant.

FIG. 20 illustrates a 3D guidance template in a hip joint, wherein thesurface of the template facing the joint is a mirror and/or negativeimage of a portion of the joint that is not affected by the arthriticprocess.

FIG. 21 illustrates a 3D guidance template for an acetabulum, whereinthe surface of the template facing the joint is a mirror and/or negativeimage of a portion of the joint that is affected by the arthriticprocess.

FIG. 22 illustrates a 3D guidance template designed to guide a posteriorcut using a posterior reference plane. The joint facing surface of thetemplate is, at least in part, a mirror image of portions of the jointthat are not altered by the arthritic process.

FIG. 23 illustrates a 3D guidance template designed to guide an anteriorcut using an anterior reference plane. The joint facing surface of thetemplate is, at least in part, a mirror image of portions of the jointthat are altered by the arthritic process.

FIG. 24 illustrates a 3D guidance template for guiding a tibial cut (notshown), wherein the tibia includes an anatomic relief surface to span anarthritic portion. The template is designed to avoid the arthriticprocess by spanning across the defect or cyst.

FIG. 25 illustrates a 3D guidance template for guiding a tibial cut, inaccordance with an alternative embodiment. The interface between normaland arthritic tissue is included in the shape of the template.

FIG. 26 A illustrates a 3D guidance template wherein the surface of thetemplate facing the joint is a mirror image of at least portions of thesurface of a joint that is healthy or substantially unaffected by thearthritic process. FIG. 26 B illustrates the 3D guidance templatewherein the surface of the template facing the joint is a mirror imageof at least portions of the surface of the joint that is healthy orsubstantially unaffected by the arthritic process. The diseased area iscovered by the template, but the mold is not substantially in contactwith it. FIG. 26 C illustrates the 3D guidance template wherein thesurface of the template facing the joint is a mirror image of at leastportions of the surface of the joint that are arthritic. FIG. 26 Dillustrates the 3D guidance template wherein the template closelymirrors the shape of the interface between substantially normal or nearnormal and diseased joint tissue.

FIGS. 27 A-D show multiple molds with linkages on the same articularsurface (A-C) and to an opposing articular surface (D), in accordancewith various embodiments.

FIG. 28 illustrates a deviation in the AP plane of the femoral andtibial axes in a patient.

FIG. 29 is a flow diagram showing a method wherein measured leg lengthdiscrepancy is utilized to determine the optimal cut height of a femoralneck cut for total hip arthroplasty.

FIGS. 30 A-C illustrate the use of 3D guidance templates for performingligament repair.

FIG. 31 shows an example of treatment of CAM impingement using a 3Dguidance template.

FIG. 32 shows an example of treatment of Pincer impingement using a 3Dguidance template.

FIG. 33 shows an example of an intended site for placement of a femoralneck mold for total hip arthroplasty.

FIG. 34 shows an example of a femoral neck mold with handle and slot.

FIG. 35 shows an example of a posterior acetabular approach for totalhip replacement.

FIG. 36 shows an example of a guidance mold used for reaming the sitefor an acetabular cup.

FIG. 37 illustrates a surface of a femur prior to derivation of anarticular offset surface;

FIG. 38 illustrates an offset surface created using the femur surface ofFIG. 37;

FIG. 38 illustrates a solid model of a surgical tool overlaid over theoffset surface;

FIG. 39 illustrates merging of the offset surface to a relevant portionof the solid model;

FIGS. 40 and 41 illustrate the solid model prior to and afterincorporating the derived offset surface;

FIG. 42 illustrates a surface of a femur prior to derivation of anarticular offset surface in accordance with an alternate embodiment;

FIG. 43 illustrates a trochlear curve sketch derived using the femursurface of FIG. 42;

FIG. 44 illustrates the trochlear curve sketch of FIG. 43 laterallyexpanded and overlaid onto a solid model of a surgical tool;

FIG. 45 illustrates the solid model incorporating the derived trochlearcurve sketch;

FIG. 46 illustrates the trochlear curve sketch of FIG. 43 laterallyexpanded and overlaid onto an alternate embodiment of a surgical tool;

FIG. 47 illustrates the solid model of FIG. 46 incorporating the derivedtrochlear curve sketch;

FIG. 48 illustrates the trochlear curve sketch of FIG. 43 laterallyexpanded and overlaid onto another alternate embodiment of a surgicaltool;

FIG. 49 illustrates the solid model of FIG. 48 incorporating the derivedtrochlear curve sketch;

FIG. 50 illustrates the trochlear curve sketch of FIG. 43 laterallyexpanded and overlaid onto another alternate embodiment of a surgicaltool;

FIG. 51 A illustrates the solid model of FIG. 50 incorporating thederived trochlear curve sketch;

FIG. 51 B illustrates an alternative embodiment of a surgical toolincorporating anatomical relief surfaces;

FIG. 52 A depicts a cross-sectional cut of an end of a femur with anosteophyte surface feature;

FIG. 52 B illustrates the femur of FIG. 52 A with the cross-sectionalview of an implant/tool incorporating an anatomical relief designed tothe shape of the femur with the osteophyte intact;

FIG. 53 A is a drawing of a cross-sectional view of an end of a femurwith a subchondral void in the bone;

FIG. 53 B illustrates the femur of FIG. 53 A with a cross-sectional viewof an implant designed to the shape of the femur extending partiallywithin the void;

FIGS. 54 A through 54 D and 55 A through 55 D illustrate models for oneparticular patient receiving a single compartment knee implant;

FIGS. 56 A through 56 D and 57 A through 57 D illustrate models for oneparticular patient receiving a bicompartment knee implant;

FIG. 58 displays an image of user interface for a computer softwareprogram for generating models of patient-specific renderings of implantassembly and surface features (e.g., osteophyte structures, voids, etc),together with bone models;

FIG. 59 shows an illustrative flow chart of the high level processes ofan exemplary computer software program for generating models ofpatient-specific renderings of implant assembly and surface features(e.g., osteophyte structures, voids, etc.), together with bone models;

FIGS. 60 A and 60 B depict the posterior margin of an implant componentinclude one or more external anatomical relief surfaces selected and/ordesigned using the imaging data or shapes derived from the imaging dataso that the implant component will not interfere with and stay clear ofthe patient's PCL;

FIGS. 61 A through 61 D depict additional embodiments of implantcomponents selected and/or designed using the imaging data or shapesderived from the imaging data so that the implant stays clear of thecruciate ligament;

FIGS. 62 A through 62 C depict one alternative embodiment of a surgicaltool or jig that incorporates adjustable contact surfaces that can beextended and/or retracted;

FIGS. 63 A through 63 C depict a humeral head and upper humerus whichforms part of a shoulder joint of a patient, with various embodiments ofassociated patient-specific surgical tools;

FIGS. 64 A through 64 C depict an upper humerus and humeral head withosteophytes, with a more normalized surface that is corrected withvirtual removal of osteophytes;

FIGS. 65 A through 65 C depict an upper humerus and humeral head withvoids, fissures or cysts, with a more normalized surface that iscorrected with virtual removal of such structures;

FIGS. 66 A through 66 D depict a glenoid component of a shoulder joint,with (FIG. 66 B) virtual removal of osteophytes, and two alternativeembodiments of a glenoid jig (66 C and 66 D) which incorporate differentvariants of conforming and/or anatomical relief surfaces; and

FIGS. 67 A through 67 C depict a glenoid component of a shoulder jointwith voids, fissures or cysts, and a glenoid jig (67 C) thatincorporates one embodiment of an anatomical relief surface for engagingwith the glenoid.

DETAILED DESCRIPTION OF THE INVENTION

The following description is presented to enable any person skilled inthe art to make and use the various embodiments of devices, concepts andmethods described herein. Various modifications to the embodimentsdescribed will be readily apparent to those skilled in the art, and thegeneric principles defined herein can be applied to other embodimentsand applications without departing from the spirit and scope of thepresent systems and methods as defined by the appended claims. Thus, thepresent disclosure is not intended to be limited to the embodimentsshown, but is to be accorded the widest scope consistent with theprinciples and features disclosed herein. To the extent necessary toachieve a complete understanding of systems and methods disclosed, thespecification and drawings of all issued patents, patent publications,and patent applications cited in this application are incorporatedherein by reference.

3D guidance surgical tools, referred to herein as a 3D guidance surgicaltemplates, that may be used for surgical assistance can include, withoutlimitation, using templates, jigs and/or molds, including 3D guidancemolds. It is to be understood that the terms “template,” “jig,” “mold,”“3D guidance mold,” and “3D guidance template,” shall be usedinterchangeably within the detailed description and appended claims todescribe the tool unless the context indicates otherwise.

3D guidance surgical tools that may be used may include guide apertures.It is to be understood that the term guide aperture shall be usedinterchangeably within the detailed description and appended claims todescribe both guide surface and guide elements.

As will be appreciated by those of skill in the art, the presentdisclosure contemplates and employs the use of, unless otherwiseindicated, conventional methods of x-ray imaging and processing, x-raytomosynthesis, ultrasound including A-scan, B-scan and C-scan, computedtomography (CT scan), magnetic resonance imaging (MRI), opticalcoherence tomography, single photon emission tomography (SPECT) andpositron emission tomography (PET) within the skill of the art. Suchtechniques are explained fully in the literature. See, e.g., X-RayStructure Determination: A Practical Guide, 2nd Edition, editors Stoutand Jensen, 1989, John Wiley & Sons, publisher; Body CT: A PracticalApproach, editor Slone, 1999, McGraw-Hill publisher; X-ray Diagnosis: APhysician's Approach, editor Lam, 1998 Springer-Verlag, publisher; andDental Radiology: Understanding the X-Ray Image, editor LaetitiaBrocklebank 1997, Oxford University Press publisher. See also, TheEssential Physics of Medical Imaging (2^(nd) Ed.), Jerrold T. Bushberg,et al.

The present disclosure describes systems, methods and compositions forrepairing joints, particularly for repairing articular cartilage and forfacilitating the integration of a wide variety of cartilage repairmaterials into a subject. Among other things, the techniques describedherein allow for the customization of cartilage repair material to suita particular subject, for example in terms of size, cartilage thicknessand/or curvature. When the shape (e.g., size, thickness and/orcurvature) of the articular cartilage surface is an exact or nearanatomic fit with the non-damaged cartilage or with the subject'soriginal cartilage, the success of repair is enhanced. The repairmaterial can be shaped prior to implantation and such shaping can bebased, for example, on electronic images that provide informationregarding curvature or thickness of any “normal” cartilage surroundingthe defect and/or on curvature of the bone underlying the defect. Thus,the current disclosure provides, among other things, for minimallyinvasive methods for partial joint replacement. The methods canfacilitate only minimal or, in some instances, no loss, in bone stock.Additionally, unlike with current techniques, the methods describedherein can help to restore the integrity of the articular surface byachieving an exact or near anatomic match between the implant and thesurrounding or adjacent cartilage and/or subchondral bone.

Advantages of the various embodiments can include, but are not limitedto, (i) customization of joint repair, thereby enhancing the efficacyand comfort level for the patient following the repair procedure; (ii)eliminating the need for a surgeon to measure the defect to be repairedintraoperatively in some embodiments; (iii) eliminating the need for asurgeon to shape the material during the implantation procedure; (iv)providing methods of evaluating curvature of the repair material basedon bone or tissue images or based on intraoperative probing techniques;(v) providing methods of repairing joints with only minimal or, in someinstances, no loss in bone stock; and (vi) improving postoperative jointcongruity.

Thus, the methods described herein allow for the design and use of jointrepair material that more precisely fits the defect (e.g., site ofimplantation) and, accordingly, provides improved repair of the joint.

I. Assessment of Joints and Alignment

The methods and compositions described herein can be used to treatdefects resulting from disease of the cartilage (e.g., osteoarthritis),bone damage, cartilage damage, trauma, and/or degeneration due tooveruse or age. The various embodiments allow, among other things, ahealth practitioner to evaluate and treat such defects. The size, volumeand shape of the area of interest can include only the region ofcartilage that has the defect, but can also include contiguous parts ofthe cartilage surrounding the cartilage defect.

As will be appreciated by those of skill in the art, size, curvatureand/or thickness measurements can be obtained using any suitabletechnique. For example, one-dimensional, two-dimensional, and/orthree-dimensional measurements can be obtained using suitable mechanicalmeans, laser devices, electromagnetic or optical tracking systems,molds, materials applied to the articular surface that harden and“memorize the surface contour,” and/or one or more imaging techniquesknown in the art. Measurements can be obtained non-invasively and/orintraoperatively (e.g., using a probe or other surgical device). As willbe appreciated by those of skill in the art, the thickness of the repairdevice can vary at any given point depending upon the depth of thedamage to the cartilage and/or bone to be corrected at any particularlocation on an articular surface.

As illustrated in FIG. 1, typically the process begins by firstmeasuring the size of the area of diseased cartilage or cartilage loss10, as well the condition of the potential underlying bony anatomicalsupport structure. Thereafter the user can optionally measure thethickness of adjacent cartilage 20. Once these steps are performed, thecurvature of the articular surface is measured 30. Alternatively, thecurvature of subchondral bone can be measured.

Once the size of the defect is known, either an implant can be selectedfrom a library 32 or an implant can be generated based on the patientspecific parameters obtained in the measurements and evaluation 34.Prior to installing the implant in the joint, the implantation site isprepared 40 and then the implant is installed 42. One or more of thesesteps can be repeated as necessary or desired as shown by the optionalrepeat steps 11, 21, 31, 33, 35, and 41.

A. Imaging Techniques

I. Thickness and Curvature

As will be appreciated by those of skill in the art, imaging techniquessuitable for measuring thickness and/or curvature (e.g., of cartilageand/or bone) or size of areas of diseased cartilage or cartilage lossinclude the use of x-rays, magnetic resonance imaging (MRI), computedtomography scanning (CT, also known as computerized axial tomography orCAT), optical coherence tomography, ultrasound imaging techniques, andoptical imaging techniques. (See, also, International Patent PublicationWO 02/22014 to Alexander, et al., published Mar. 21, 2002; U.S. Pat. No.6,373,250 to Tsoref et al., issued Apr. 16, 2002; and Vandeberg et al.(2002) Radiology 222:430-436). Contrast or other enhancing agents can beemployed using any route of administration, e.g. intravenous,intra-articular, etc.

Based on the imaging performed, the software may evaluate the fit ofdifferent implants and/or surgical guide templates with regard todimensions, overall size and shape. The dimensions, overall size andshape may be optimized with regard to cortical bone shape anddimensions, cortical bone thickness, endosteal bone shape, size ofmarrow cavity, articular surface shape and dimensions, subchondral boneshape and dimensions, or subchondral bone thickness. Thus, for example,an implant may either be custom made or selected from a number ofpre-manufactured implants that is optimized with regard to any of thefollowing or combinations thereof: AP dimensions and shape, mediolateraldimensions and shape, superoinferior dimensions and shape, shape of thearticulating surface, shape and dimensions of the interface in contactwith cortical bone, shape and dimensions of intramedullary portions orcomponents. These parameters may also be optimized for implant function,e.g. for different degrees of joint flexion or extension or abduction oradduction or internal or external rotation.

In certain embodiments, CT or MRI is used to assess tissue, bone,cartilage and any defects therein, for example cartilage lesions orareas of diseased cartilage, to obtain information on subchondral boneor cartilage degeneration and to provide morphologic or biochemical orbiomechanical information about the area of damage. Specifically,changes such as fissuring, partial or full thickness cartilage loss, andsignal changes within residual cartilage can be detected using one ormore of these methods. For discussions of the basic NMR principles andtechniques, see MRI Basic Principles and Applications, Second Edition,Mark A. Brown and Richard C. Semelka, Wiley-Liss, Inc. (1999). For adiscussion of MRI including conventional T1 and T2-weighted spin-echoimaging, gradient recalled echo (GRE) imaging, magnetization transfercontrast (MTC) imaging, fast spin-echo (FSE) imaging, contrast enhancedimaging, rapid acquisition relaxation enhancement (RARE) imaging,gradient echo acquisition in the steady state (GRASS), and drivenequilibrium Fourier transform (DEFT) imaging, to obtain information oncartilage, see Alexander, et al., WO 02/22014. Other techniques includesteady state free precision, flexible equilibrium MRI and DESS. Thus, invarious embodiments, the measurements produced are based onthree-dimensional images of the joint obtained as described inAlexander, et al., WO 02/22014 or sets of two-dimensional imagesultimately yielding 3D information. Two-dimensional, andthree-dimensional images, or maps, of the cartilage alone or incombination with a movement pattern of the joint, e.g.flexion—extension, translation and/or rotation, can be obtained.Three-dimensional images can include information on movement patterns,contact points, contact zone of two or more opposing articular surfaces,and movement of the contact point or zone during joint motion. Two- andthree-dimensional images can include information on biochemicalcomposition of the articular cartilage. In addition, imaging techniquescan be compared over time, for example to provide up-to-date informationon the shape and type of repair material needed.

Traditional CT and MRI scans utilize two dimensional cross-sectionalimages acquired in different imaging planes to visualize complexthree-dimensional articular anatomy. With computed tomography, theseslices are typically acquired in the axial plane. The in-planeresolution is typically on the order of 0.25×0.25 millimeters. The slicethickness may vary from one to five millimeters. Thus, the resolutionobtained with these imaging studies is not isotropic. Moreover, the CTslices and, similarly with MRI, may be separated by one or moremillimeters. This means that the resolution of the images is excellentwithin the imaging plane. However, two to ten-fold loss in imageresolution can be encountered in a plane perpendicular to the slicesacquired by the CT or MRI scanner. This limitation in resolutionperpendicular to the imaging plane can result in inaccuracies inderiving the three-dimensional shape of, without limitation, an implantand/or a 3-D guidance template, described in more detail below.

In accordance with one embodiment, spiral CT imaging is utilized toacquire the images rather than standard CT technology. With recent CTtechnology, slip ring technology is incorporated in the scanner. A slipring is a circular contact with sliding brushes that allows the gantryto rotate continuously, untethered by electrical wires. The use of slipring technology eliminates the initial limitations at the end of eachslice acquisition. Thus, the rotating gantry is free to rotatecontinuously throughout the examination of a joint. A slip ring CTscanner design allows greater rotational velocities, thereby shorteningscan times. With a spiral CT scan data is acquired while the table ismoving. As a result, the x-ray source moves in a spiral or helicalrather than a circular pattern around the patient. The speed of thetable motion relative to the rotation of the CT gantry is often aconsideration for image quality in helical or spiral CT scanning. Thisparameter is call pitch. In one embodiment, spiral CT scans will beacquired through the joint wherein these spiral CT scans afford aresolution that is isotropic, for example 1 millimeter by 1 millimeterby 1 millimeter in x, y and z direction, or 0.75×0.75×0.75 millimetersin x, y and z direction, or 0.5×0.5×0.5 millimeters in x, y and zdirection, or 0.25×0.25×0.25 millimeters in x, y and z direction. Nearisotropic data sets are also acceptable particularly if the maximumresolution in any one of the three special orientations does not exceed1.5 millimeters, or 1.0 millimeters, or 0.75 millimeters, or 0.5millimeters. Thus, the various embodiments recognize that the accuracyin placing a 3-D guidance template on an articular surface, or shapingan implant, can be greatly improved with isotropic or near isotropicdata sets as compared to traditional 2-D slice based data sets derivedfrom either CT or MRI or other imaging technologies. For example, a kneejoint scan data acquired with near isotropic resolution of 0.4×0.4×0.7millimeters (e.g. a resolution ratio of less than 2:1 between thedifferent dimensions and resolution in all three dimensions may be moredesirable than 1 mm) will yield greater positional accuracy in placing a3-D guidance template on the articular surface than scan data acquiredusing traditional CT scans, for example, with a scan resolution of0.4×0.4×1.2 millimeters.

With MRI, standard acquisition call sequences also result in twodimensional slices for displaying complex three dimensional articularanatomy. The two dimensional slices can be acquired using 2-D or 3-DFourier transformation. After the 2-D or 3-D transform, 2-D slices areavailable for image viewing and image processing. Of note, typically theimage resolution in the imaging plane will be two or more fold greaterthan the image resolution perpendicular to the primary imaging plane.Similar to CT, this limitation in spatial resolution in the planeperpendicular to the imaging plane can result in inaccuracies inderiving and subsequently placing 3-D guidance molds. In one embodiment,MRI data is acquired or processed so that the data used for generatingthe 3-D guidance mold or implant has isotropic or near isotropicresolution. For example, isotropic or near isotropic resolution may beachieved by fusing two non-parallel imaging planes acquired usingstandard 2-D or 3-D Fourier transform images, registering them relativeto each other and performing an image fusion (see U.S. patentapplication Ser. No. 10/728,731, entitled “FUSION OF MULTIPLE IMAGINGPLANES FOR ISOTROPIC IMAGING IN MRI AND QUANTITATIVE IMAGE ANALYSISUSING ISOTROPIC OR NEAR-ISOTROPIC IMAGING,” hereby incorporated byreference in its entirety). Alternatively, using latest generation scantechnology, for example, with 3-D FSE, 3-D DESS, 3-D MENSA, 3-D PAVA,3-D LAVA, 3-D MERGE, 3-D MEDIC imaging sequences, multi-channel coils,high field magnets, advanced gradient technology, isotropic or nearisotropic acquisition using 3-D Fourier transform can be obtained. Usingsuch advanced imaging technology, image resolution of 0.5 by 0.5 by 0.8millimeters or greater may be obtained, achieving near isotropic andeven isotropic resolution, with resolution in all three dimensions ofless than 1 mm.

As will be appreciated by those of skill in the art, imaging techniquescan be combined, if desired. For example, C-arm imaging or x-rayfluoroscopy can be used for motion imaging, while MRI can yield highresolution cartilage information. C-arm imaging can be combined withintra-articular contrast to visualize the cartilage.

Any of the imaging devices described herein can also be usedintra-operatively (see, also below), for example using a hand-heldultrasound and/or optical probe to image the articular surfaceintra-operatively.

ii. Anatomical and Mechanical Axes, Virtual Ligament Balancing

Imaging can be used to determine the anatomical and biomechanical axesof an extremity associated with a joint, which can then be used increating an implant or surgical guide template or mold. Suitable testsinclude, for example, an x-ray, or an x-ray combined with an MRI.Typically, anatomical landmarks are identified on the imaging testresults (e.g., the x-ray film) and those landmarks are then utilized todirectly or indirectly determine the desired axes. Thus, for example, ifsurgery is contemplated in a hip joint, knee joint, or ankle joint, anx-ray can be obtained. This x-ray can be a weight-bearing film of theextremity, for example, a full-length leg film taken while the patientis standing. This film can be used to determine the femoral and tibialanatomical axes and to estimate the biomechanical axes. As will beappreciated by those of skill in the art, these processes foridentifying, e.g., anatomical and biomechanical axis of the joint can beapplied to other joints without departing from the scope of theinvention.

Anatomical and biomechanical axes can also be determined using otherimaging modalities, including but not limited to, computed tomographyand MRI. For example, a CT scan can be obtained through the hip joint,the knee joint, and the ankle joint. Optionally, the scan can bereformatted in the sagittal, coronal, or other planes. The CT images canthen be utilized to identify anatomical landmarks and to determine theanatomical and biomechanical axes of the hip joint, knee joint, and/orankle joint.

Similarly, an MRI scan can be obtained for this purpose. For example, anMRI scan of the thigh and pelvic region can be obtained using a bodycoil or a torso phased array coil. A high resolution scan of the kneejoint can be obtained using a dedicated extremity coil. A scan of thecalf/tibia region and the ankle joint can be obtained again using a bodycoil or a torso phased array coil. Anatomical landmarks can beidentified in each joint on these scans and the anatomical andbiomechanical axes can be estimated using this information.

In various embodiments, the imaging scan can be extended for 5 cm, 10 cmor more, including 15 cm above and/or below the joint, thereby derivinganatomic information that can be used to derive the anatomic andbiomechanical axis. For example, an MRI or CT scan can be obtainedthrough a knee joint. The scan can extend 15 cm above and below thejoint. The mid-femoral line and mid-tibial line as well as otheranatomic landmarks such as the femoral transepicondylar line orWhiteside line or posterior condylar line can be determined and can beused to estimate the anatomic and biomechanical axes. Thus, in theexample of a knee joint, no additional scanning through the hip jointand ankle joints will be absolutely required.

With, for example, MRI, even larger coverage may be obtained, forexample with a series of axial, sagittal or coronal slices obtained witha large field of view, e.g. 20 cm or more, or 25 cm or more, or 30 cm ormore, or 35 cm or more. These large field of view scans can be utilizedto estimate the anatomic and biomechanical axes as described above. Invarious situations, they can lack information on the surface detail ofthe joint due to limitations in spatial resolution. A second oradditional scan can be performed with high resolution, e.g. with spatialresolution and x and y axis of less than 1.0 mm, or less than 0.8 mm, orless than 0.6 mm. The additional high resolution scan may be utilized toderive the articular surface detail adequate for a good and accurate fitbetween the guidance template or implant, and the articular surface oradjacent structures.

A biomechanical axis and, in some instances, an anatomical axis mayadvantageously be defined by imaging the entire extremity in question.Such imaging may include cross-sectional, spiral or volumetric imagingvia a CT or MRI scan or optical imaging through the entire extremity, oracquisition of select images or slices or volumes through an area ofinterest such as a hip joint, a knee joint or ankle joint.

In an illustrative embodiment, scans through the entire or portions ofan entire extremity covering multiple joints may be replaced with anextended scan through a single joint such as a knee joint. For example,it may not be sufficient to estimate a biomechanical axis or ananatomical access with a standard knee scan such as a CT scan or MRIscan that includes, for example, only ten centimeter of the area orvolume of interest above, or ten centimeters of area or volume ofinterest below the tibiofemoral joints space. With an extended scan, alarger area adjacent to the target joint can be included in the scan,e.g. fifteen centimeters above and below the medial tibia femoral jointspace, twenty centimeters above and below the medial tibia femoral jointspace, fifteen centimeters above and twenty centimeters below the medialtibiofemoral joint space, twenty centimeters above and twenty-fivecentimeters below the medial tibiofemoral joint space. While theextended scan is less involved on the operative side than the scaninvolving the neighboring joints, it can, optionally be used to providean estimate of the anatomical axis, biomechanical axis, and/or animplant axes or related planes. Thus, better ease of use is provided atthe expense of, possibly, more radiation and possibly, less accuracy.

In another embodiment, cross-sectional or volumetric images such as CTscans or MRI scans may be acquired through more than one joint,typically one or more joints neighboring the one contemplated forsurgery. For example, CT or MRI slices, CT spirals, CT or MRI volumes,MRI two plane acquisitions with optional image fusion, or othertomographic acquisitions are acquired through the hip joint, knee jointand ankle joint in a patient scheduled for total knee replacementsurgery. The 3D surgical guidance templates may be optimized by usinganatomic and/or biomechanical information obtained in the adjacentneighboring joints, for example, resulting in an improved anatomic orfunctional result. By using cross-sectional or volumetric imaginginformation, more accurate identification of anatomic landmarks foridentifying relevant anatomical and/or biomechanical axis, relevantplanes including surgical planes and implant planes, as well as implantaxes can be achieved when compared to x-rays or CT scout scans, inparticular when the cross-sectional or volumetric data are acquiredthrough neighboring joints. The accuracy of the position, orientation,shape or combinations thereof, of a 3D guide template can thus beimproved with resulting improvement in accuracy of the surgicalcorrection of underlying deformities such as varus, valgus, abduction,adduction, or rotation deformities.

An imaging test obtained during weight-bearing conditions has someinherent advantages, in that it demonstrates normal as well aspathological loading and load distribution. A cross-sectional imagingstudy such as a CT scan or MRI scan has some advantages because itallows one to visualize and demonstrate the anatomical landmarks inthree, rather than two, dimensions, thereby adding accuracy. Moreover,measurements can be performed in other planes, such as the sagittal oroblique planes, that may not be easily accessible in certain anatomicalregions using conventional radiography. In principle, any imaging testcan be utilized for this purpose.

The biomechanical axis can be defined as the axis going from the centerof the femoral head, between the condylar surfaces and through the anklejoint

The software may automatically, semi-automatically or manually assistedfind or identify the relevant anatomic points to calculate the anatomicand biomechanical axes, in accordance with various embodiments. Forexample, the software or the user can find the center of the femoralhead. Optionally, this can be done in 3D rather than only in 2D. Thus,for example, in the femoral head, the software can find the center ofthe femoral head relative to its x, y, and z-dimensions. Alternatively,the relevant anatomic points can be selected manually and the axes canbe calculated.

In another embodiment the software can compute methods of adjustingvarus or valgus or ante- or retroversion deformity or rotationaldeformity based on such anatomic and biomechanical axis measurements.For example, the surface of a surgical guide template can be adapted sothat surgical cuts performed for a total knee implant can be placed tocorrect an underlying varus or valgus deformity or, for example, ante-or retroversion. Alternatively, the openings/cut planes of a surgicalguide template used for drilling, cutting and the like can be adjustedto achieve a varus or valgus correction to a near anatomic orphysiologic range. These adjustments can be optimized for the implantsof different manufacturers, e.g. Johnson & Johnson, Stryker, Smith &Nephew, Biomet and Zimmer.

In various embodiments, gait, loading and other physical activities of ajoint as well as static joint positions may be simulated using acomputer workstation. The template and its apertures and the resultantsurgical templates and/or procedures, e.g. cuts, drilling, rasping, maybe optimized using this information to achieve an optimal functionalresult. For example, the template and its apertures and the resultantimplant position may be optimized for different degrees of flexion andextension, internal or external rotation, abduction or adduction, andante or retroversion. Thus, the templates may be used to achieve motionthat is optimized in one, two or more directions. Not only anatomic, butalso functional optimization is possible in this manner.

The origin and insertion of ligaments, e.g. the anterior and posteriorcruciate ligaments and the medial and lateral collateral ligaments inthe case of a knee, can be visualized on the scan. With MRI, theligaments are directly visible. If the ligament is torn, the location ofthe residual fibers at the origin or attachment can be visualized.Different joint positions can then be simulated and changes in ligamentlength can be determined for different angles of flexion and extension,internal or external rotation, abduction or adduction, and ante orretroversion. These simulations can be performed without but also withthe implant in place. Thus, ligament length—and through this presumedtension—can be estimated virtually with any given implant and implantsize. Different implants or component(s) can be tested preoperatively onthe computer workstation and the implant or component(s) yielding theoptimal ligament performance, e.g. minimal change in ligament length,for different joint positions can be determined pre-operatively. Thus,the various embodiments provide, among others, for pre-operativeligament balancing, including but not limited to by directly visualizingthe ligaments or fiber remnants.

For example, in one embodiment a loading apparatus may be applied to thepatient to simulate weight-bearing while acquiring the CT scan. Anon-limiting example of such a loading apparatus has been described byDynamed with the Dynawell device. Any loading apparatus that can applyaxial or other physiologic or near physiologic loading forces on thehip, knee or ankle joints or two or three of them may be used. Othermore sophisticated scanning procedures can be used to derive thisinformation without departing from the scope of the invention.

In one embodiment, when imaging a joint of the lower extremity, astanding, weight-bearing x-ray can be obtained to determine thebiomechanical axis. In the case of a knee or hip joint, for example, astanding, weight-bearing x-ray of the hip joint or the knee joint can beobtained. Alternatively, standing, weight-bearing x-rays can be obtainedspanning the entire leg from the hip to the foot. The x-ray can beobtained in the antero-posterior or posterior-anterior projection butalso in a lateral projection or principally any other projection that isdesired. The user can measure the biomechanical axis, for example, byfinding the centroid of the femoral head and the centroid of the anklejoint and by connecting these. This measurement can be performedmanually, for example, on a x-ray film or electronically, for example,on a digitized or digital image, including with software assistance. Theaxis measured on the standing, weight-bearing x-ray can be crossreferenced with another imaging modality such a CT or MRI scan. Forexample, a biomechanical axis can be determined on a standing x-ray ofthe leg. The result and data can be cross referenced, for example, byidentifying corresponding bony anatomical landmarks to a CT scan or MRIscan. The result and information can then be utilized to determine theoptimal shape of a 3-D guidance template. Specifically, the orientation,position, or shape of the template can be influenced based on themeasurement of the biomechanical axis. Moreover, the position or shapeof any blocks attached to said templates or linkages or the position orshape instruments attached to the mold, block or linkages can beinfluenced by this measurement. Combining the standing, weight-bearingimaging modality with CT scanning or MRI scanning has the principleadvantage that the joint is evaluated during physiological loading. CTor MRI alone, typically do not afford assessment in loaded,weight-bearing condition.

As described above, the biomechanical axis can be evaluated in differentplanes or in three dimensions. For example, the actual biomechanicalaxis can be assessed in the AP plane and a desired biomechanical axiscan be determined in this plane. In addition, the actual biomechanicalaxis can be determined in the lateral plane, for example, in the lateralprojection radiograph, and the desired biomechanical axis can bedetermined in the lateral plane. By measuring the relevant biomechanicaland anatomical axis in two or more planes, the shape of a 3-D guidancetemplate and/or implant can be further refined and optimized with resultin improvements in clinical and patient function.

The biomechanical or anatomical axis may also be measured using otherapproaches including a non-weight bearing position. For example,anatomical landmarks can be identified on a CT scout scan and crossreferenced to a joint such as a knee joint or a hip joint for whichsurgery is contemplated. Thus, for example, the user can measure anddetermine the centroid of the ankle joint and the centroid of the hipjoint for knee surgery using the CT scout scan.

In one embodiment, the anatomical landmarks are determined using CTslices or MRI slices rather than a scout scan. A CT scout scan or MRIscout scan can have inherent limitations in spatial resolution. A CTscout scan is typically a single, 2-D radiographic image of theextremity lacking 3-D anatomical information and lacking high spatialresolution. An MRI scout scan is typically composed of multiple 2-D MRIslices, possibly acquired in one, two, or three planes. However, theresolution of the MRI scout scan is typically also limited. By acquiringselective slices and even isotropic or near isotropic data sets throughneighboring joints, anatomical landmarks can be identified in a morereliable manner thereby improving the accuracy of anatomical andbiomechanical axis determination. This improvement in accuracytranslates into an improvement in accuracy in the resultant 3-D guidancemold, for example, a knee or hip joint, including improved accuracy ofits shape, orientation, or position.

Computed Tomography imaging has been shown to be highly accurate for thedetermination of the relative anatomical and biomechanical axes of theleg (Testi Debora, Zannoni Cinzia, Cappello Angelo and Viceconti Marco.“Border tracing algorithm implementation for the femoral geometryreconstruction.” Comp. Meth. and Programs in Biomed., Feb. 14, 2000;Farrar M J, Newman R J, Mawhinney R R, King R. “Computed tomography scanscout film for measurement of femoral axis in knee arthroplasty.” J.Arthroplasty. 1999 December; 14(8): 1030-1; Kim J S, Park T S, Park S B,Kim J S, Kim I Y, Kim S I. “Measurement of femoral neck anteversion in3D. Part 1: 3D imaging method.” Med. and Biol. Eng. and Computing.38(6): 603-609, November 2000; Akagi M, Yamashita E, Nakagawa T, AsanoT, Nakamura T. “Relationship between frontal knee alignment andreference axis in the distal femur.” Clin. Ortho. and Related Res. No.388, 147-156, 2001; Mahaisavariya B, Sitthiseripratip K, Tongdee T,Bohez E, Sloten J V, Oris P. “Morphological study of the proximal femur:a new method of geometrical assessment using 3 dimensional reverseengineering.” Med. Eng. and Phys. 24 (2002) 617-622; Lam Li On,Shakespeare D. “Varus/Valgus alignment of the femoral component in totalknee arthroplasty.” The Knee, 10 (2003) 237-241).

The angles of the anatomical structures of the proximal and distal femuralso show a certain variability level (i.e. standard deviation)comparable with the varus or valgus angle or the angle between theanatomical femoral axis and the biomechanical axis (Mahaisavariya B,Sitthiseripratip K, Tongdee T, Bohez E, Sloten J V, Oris P.“Morphological study of the proximal femur: a new method of geometricalassessment using 3 dimensional reverse engineering.” Med. Eng. and Phys.24 (2002) 617-622). Thus, one approach for assessing the axes can bebased on CT scans of the hip, knee and ankle joint or femur rather thanonly of the knee region.

CT has been shown to be efficient in terms of the contrast of the bonetissue with respect to surrounding anatomical tissue so the bonestructures corresponding to the femur and tibia can be extracted veryaccurately with semi automated computerized systems (Mahaisavariya B,Sitthiseripratip K, Tongdee T, Bohez E, Sloten J V, Oris P.“Morphological study of the proximal femur: a new method of geometricalassessment using 3 dimensional reverse engineering.” Med. Eng. and Phys.24 (2002) 617-622; Testi Debora, Zannoni Cinzia, Cappello Angelo andViceconti Marco. “Border tracing algorithm implementation for thefemoral geometry reconstruction.” Comp. Meth. and Programs in Biomed.,Feb. 14, 2000).

While 2-D CT has been shown to be accurate in the estimation of thebiomechanical axis (Mahaisavariya B, Sitthiseripratip K, Tongdee T,Bohez E, Sloten J V, Oris P. “Morphological study of the proximal femur:a new method of geometrical assessment using 3 dimensional reverseengineering.” Med. Eng. and Phys. 24 (2002) 617-622; Testi Debora,supra.; Lam Li On, Supra, 3-D CT has been shown to be more accurate forthe estimation of the femoral anteversion angle (Kim J S, Park T S, ParkS B, Kim J S, Kim I Y, Kim S I. Measurement of femoral neck anteversionin 3D. Part 1: 3D imaging method. Medical and Biological engineering andcomputing. 38(6): 603-609, November 2000; Kim J S, Park T S, Park S B,Kim J S, Kim I Y, Kim S I. Measurement of femoral neck anteversion in3D. Part 1: 3D modeling method. Medical and Biological engineering andcomputing. 38(6): 610-616, November 2000). Farrar used simple CT 2-Dscout views to estimate the femoral axis (Farrar M J, Newman R J,Mawhinney R R, King R. Computed tomography scan scout film formeasurement of femoral axis in knee arthroplasty. J. Arthroplasty. 1999December; 14(8): 1030-1).

In one embodiment, 2-D sagittal and coronal reconstructions of CT sliceimages are used to manually estimate the biomechanical axis. One skilledin the art can easily recognize many different ways to automate thisprocess. For example, a CT scan covering at least the hip, knee andankle region is acquired. This results in image slices (axial) which canbe interpolated to generate the sagittal and coronal views.

Preprocessing (filtering) of the slice images can be used to improve thecontrast of the bone regions so that they can be extracted accuratelyusing simple thresholding or a more involved image segmentation toollike LiveWire or active contour models.

Identification of landmarks of interest like the centroid of the tibialshaft, the ankle joint, the intercondylar notch and the centroid of thefemoral head can be performed. The biomechanical axis can be defined asthe line connecting the proximal and the distal centroids, i.e. thefemoral head centroid, the tibial or ankle joint centroid. The positionof the intercondylar notch can be used for evaluation of possibledeviations, errors or deformations including varus and valgus deformity.

In one embodiment, multiple imaging tests can be combined. For example,the anatomical and biomechanical axes can be estimated using aweight-bearing x-ray of the extremity or portions of the extremity. Theanatomical information derived in this fashion can then be combined witha CT or MRI scan of one or more joints, such as a hip, knee, or anklejoint. Landmarks seen on radiography can then, for example, becross-referenced on the CT or MRI scan. Axis measurements performed onradiography can be subsequently applied to the CT or MRI scans or otherimaging modalities. Similarly, the information obtained from a CT scancan be compared with that obtained with an MRI or ultrasound scan. Inone embodiment, image fusion of different imaging modalities can beperformed. For example, if surgery is contemplated in a knee joint, afull-length weight-bearing x-ray of the lower extremity can be obtained.This can be supplemented by a spiral CT scan, optionally withintra-articular contrast of the knee joint providing high resolutionthree-dimensional anatomical characterization of the knee anatomy evenincluding the menisci and cartilage. This information, along with theaxis information provided by the radiograph can be utilized to select orderive therapies, such as implants or surgical instruments.

In certain embodiments, it may be desirable to characterize the shapeand dimension of intra-articular structures, including subchondral boneor the cartilage. This may be done, for example, by using a CT scan or aspiral CT scan of one or more joints. The spiral CT scan can optionallybe performed using intra-articular contrast. Alternatively, an MRI scancan be performed. If CT is utilized, a full spiral scan, or a fewselected slices, can be obtained through neighboring joints. Typically,a full spiral scan providing full three-dimensional characterizationwould be obtained in the joint for which therapy is contemplated. Ifimplants, or templates, for surgical instruments are selected or shaped,using this scan, the subchondral bone shape can be accurately determinedfrom the resultant image data. A standard cartilage thickness and,similarly, a standard cartilage loss can be assumed in certain regionsof the articular surface. For example, a standard thickness of 2 mm ofthe articular cartilage can be applied to the subchondral bone in theanterior third of the medial and lateral femoral condyles. Similarly, astandard thickness of 2 mm of the articular cartilage can be applied tothe subchondral bone in the posterior third of the medial and lateralfemoral condyles. A standard thickness of 0 mm of the articularcartilage can be applied in the central weight-bearing zone of themedial condyle, and a different value can be applied to the lateralcondyle. The transition between these zones can be gradual, for example,from 2 mm to 0 mm. These standard values of estimated cartilagethickness and cartilage loss in different regions of the joint canoptionally be derived from a reference database. The reference databasecan include categories such as age, body mass index (“BMI”), severity ofdisease, pain, severity of varus deformity, severity of valgusdeformity, Kellgren-Lawrence score, along with other parameters that aredetermined to be relative and useful. Use of a standard thickness forthe articular cartilage can facilitate the imaging protocols requiredfor pre-operative planning.

Alternatively, however, the articular cartilage can be fullycharacterized by performing a spiral CT scan of the joint in thepresence of intra-articular contrast or by performing an MRI scan usingcartilage sensitive pulse sequences.

The techniques described herein can be used to obtain an image of ajoint that is stationary, either weight bearing or not, or in motion orcombinations thereof. Imaging studies that are obtained during jointmotion can be useful for assessing the load bearing surface. This can beadvantageous for designing or selecting implants, e.g. for selectingreinforcements in high load areas, for surgical tools and for implantplacement, e.g. for optimizing implant alignment relative to high loadareas.

iii. Joint Space

In accordance with another embodiment, a method and system fordetermining joint space width is provided. Without limitation, a CTscan, MRI scan, optical scan, and/or ultrasound imaging is performed.The medial and lateral joint space width in a knee joint, the jointspace in a hip joint, ankle joint or other joint is evaluated. Thisevaluation may be performed in two dimensions, using a single scan planeorientation, such as sagittal or coronal plane, or it may be performedin three dimensions. The evaluation of joint space width may includemeasuring the distance from the subchondral bone plate of one articularsurface to the subchondral bone plate of the opposing articular surface.Alternatively, the cartilage thickness may be measured directly on oneor more articular surfaces. Joint space width or cartilage thickness maybe measured for different regions of the joint and joint space width andcartilage loss can be evaluated in anterior, posterior, medial, lateral,superior and/or inferior positions. The measurements may be performedfor different positions of the joint such as a neutral position, 45degrees of flexion, 90 degrees of flexion, 5 degrees of abduction, 5degrees of internal rotation and so forth. For example, in a knee joint,the joint space width may be evaluated in extension and at 25 degrees ofknee flexion and 90 degrees of knee flexion. The medial and lateraljoint space width may be compared and differences in medial and lateraljoint space width can be utilized to optimize the desired postoperativecorrection in anatomical or biomechanical axis alignment based on thisinformation. The shape, orientation, or position of a 3D guided templatemay be adjusted using this information, for example, in knee or hipimplant placement or other surgeries.

For example, the measurement may show reduced joint space width orcartilage thickness in the medial compartment when compared to a normalanatomic reference standard, e.g. from age or sex or gender matchedcontrols, and/or lateral compartment. This can coincide with valgusalignment of the knee joint, measured, for example, on the scout scan ofan CT-scan or the localizer scan of an MRI scan including multiplelocalizer scans through the hip, knee and ankle joints.

If the biomechanical axis estimated on the comparison of the medial andlateral joint space width coincides with the biomechanical axis of theextremity measured on the scout scan, no further adjustment may benecessary. If the biomechanical axis estimated on the comparison of themedial and lateral joint space width does not coincide with thebiomechanical axis of the extremity measured on the CT or MRI scoutscan, additional correction of the valgus deformity (or in otherembodiments, varus or other deformities) can be achieved.

This additional correction may be determined, for example, by adding thedifference in axis correction desired based on biomechanical axismeasured by comparison of the medial lateral joint space width and axiscorrection desired based on measurement of the biomechanical axis of theextremity measured on the scout or localizer scan to axis correctiondesired based on measurement of the biomechanical axis of the extremitymeasured on the scout or localizer scan alone. By combining theinformation from both, measurement of joint space width of the medianand lateral compartment and measurement of the biomechanical axis usingthe scout scan or localizer scan or, for example, a weight bearingx-ray, an improved assessment of axis alignment during load bearingconditions can be obtained with resultant improvements in the shape,orientation or position of the 3D guidance template and relatedattachments or linkages.

Optionally, the extremity can be loaded while in the scanner, forexample, using a compression harness. Examples for compression harnesseshave been published, for example, by Dynawell.

iv. Estimation of Cartilage Loss

In another embodiment, an imaging modality such as spiral CT, spiral CTarthography, MRI, optical imaging, optical coherence tomography,ultrasound and others may be used to estimate cartilage loss in one, twoor three dimensions. The information can be used to determine a desiredcorrection of a measured biomechanical or anatomical axis. Thecorrection can be in the anterior-posterior, medio-lateral, and/orsuper-inferior direction, or any other direction applicable ordesirable, or combinations thereof. The information can be combined withother data e.g., from a standing, weight bearing x-ray or CT scout scan,or an MRI localizer scan or a CT scan or MRI scan that includesaxial/spiral or other images through the hip, knee and ankle joints. Theinformation can be used to refine the axis correction desired based on,for example, standing x-rays, non-weight bearing x-rays, CT scout scans,MRI localizer scans and the like.

In another embodiment, any axis correction can be performed in a singleplane (e.g., the medial-lateral plane), in two planes (e.g., the mediallateral and anterior-posterior planes), or multiple planes, includingoblique planes that are biomechanically or anatomically relevant ordesirable.

v. High Resolution Imaging

Additional improvements in accuracy of the 3D guide template and/orimplants surfaces may be obtained with use of imaging technology thatyields high spatial resolution, not only within the imaging plane, butalong all three planes, specifically the X, Y and Z axis. With CTscanning, this can be achieved with the advent of spiral CT Scanningtechniques. With MRI, dual or more plane scanning or volumetricacquisition can be performed. If dual or more plane MRI scanning isperformed, these multiple scan planes can be fused, for example bycross-registration and resampling along the X, Y and Z axis. Theresultant effective resolution in X, Y and Z direction is greatlyimproved as compared to standard CT scanning or standard MRI scanning.Improvements in resolution have the advantage that the resultant 3Dguide templates can be substantially more accurate, for example withregard to their position, shape or orientation.

vi. Phantom Scans

Imaging modalities are subject to scan to scan variations, for example,including spatial distortion. In one embodiment, phantom scans may beperformed in order to optimize the scan quality, specifically spatialresolution and spatial distortion. A phantom scan can be performed priorto a patient scan, simultaneously with a patient scan or after a patientscan. Using the phantom scan data, it is possible to make adjustmentsand optimizations of the scanner and, moreover, to perform image postprocessing to perform corrections, for example, correction of geometricdistortions. Thus, if a phantom scan detects certain geometricdistortion in the X, Y or Z axis and the amount of distortion ismeasured on the phantom scan, a correction factor can be included in thedata prior to generating a 3D guide template. The resulting 3D guidetemplate is thus more accurate with resulting improvement inintra-operative cross-reference to the anatomic surface and resultantimproved accuracy in any surgical intervention such as drilling orcutting. In various embodiments, the areas of distortion can beidentified and/or indicated on any relevant images, including where suchdistortions have been “corrected” or otherwise altered from theiroriginal, initial or raw data.

In another embodiment, a smoothing operation, e.g. using low frequencyfiltering, can be performed in order to remove any image relatedartifacts, such as stepping artifacts between adjacent CT or MRI slices.In some applications, the smoothing operation can be helpful inimproving the fit between the joint and the template. In variousembodiments, the areas of smoothing or other image alterations can beidentified and/or indicated on any relevant images, including where suchalterations have “corrected” or otherwise altered the image informationfrom an original, initial, raw or preprocessed data state.

B. Intraoperative Measurements

Alternatively, or in addition to, non-invasive imaging techniquesdescribed above, measurements of the size of an area of diseasedcartilage or an area of cartilage loss, measurements of cartilagethickness and/or curvature of cartilage or bone can be obtainedintraoperatively during arthroscopy or open arthrotomy. Intraoperativemeasurements can, but need not, involve actual contact with one or moreareas of the articular surfaces.

Devices suitable for obtaining intraoperative measurements of cartilageor bone or other articular structures, and to generate a topographicalmap of the surface include but are not limited to, Placido disks,optical measurements tools and device, optical imaging tools anddevices, and laser interferometers, and/or deformable materials ordevices. (See, for example, U.S. Pat. Nos. 6,382,028 to Wooh et al.,issued May 7, 2002; 6,057,927 to Levesque et al., issued May 2, 2000;5,523,843 to Yamane et al. issued Jun. 4, 1996; 5,847,804 to Sarver etal. issued Dec. 8, 1998; and 5,684,562 to Fujieda, issued Nov. 4, 1997).

In alternative embodiments, an optical imaging device or measurementtool, e.g. a laser interferometer, can also be attached to the end of anendoscopic device. Optionally, a small sensor can be attached to thedevice in order to determine the cartilage surface or bone curvatureusing phase shift interferometry, producing a fringe pattern analysisphase map (wave front) visualization of the cartilage surface. Thecurvature can then be visualized on a monitor as a color coded,topographical map of the cartilage surface. Additionally, a mathematicalmodel of the topographical map can be used to determine the idealsurface topography to replace any cartilage or bone defects in the areaanalyzed. This computed, ideal surface, or surfaces, can then bevisualized on the monitor, and can be used to select the curvature, orcurvatures, of the replacement cartilage or mold.

Optical imaging techniques can be utilized to generate a 3Dvisualization or surface map of the cartilage or bone, which can be usedto generate an articular repair system or a mold. One skilled in the artwill readily recognize that other techniques for optical measurements ofthe cartilage surface curvature can be employed without departing fromthe scope of the invention. For example, a 2-dimensional or3-dimensional map can be generated.

Other devices to measure cartilage and subchondral bone intraoperativelyinclude, for example, ultrasound probes. An ultrasound probe, includinga handheld probe, can be applied to the cartilage and the curvature ofthe cartilage and/or the subchondral bone can be measured. Moreover, thesize of a cartilage defect can be assessed and the thickness of thearticular cartilage can be determined. Such ultrasound measurements canbe obtained in A-mode, B-mode, or C-mode. If A-mode measurements areobtained, an operator can typically repeat the measurements with severaldifferent probe orientations, e.g. mediolateral and anteroposterior, inorder to derive a three-dimensional assessment of size, curvature andthickness.

One skilled in the art will easily recognize that different probedesigns are possible using optical, laser interferometry, mechanical andultrasound probes. The probes may be handheld. In certain embodiments,the probes or at least a portion of the probe, typically the portionthat is in contact with the tissue, can be sterile. Sterility can beachieved with use of sterile covers, for example similar to thosedisclosed in WO 99/08598A1 to Lang, published Feb. 25, 1999.

Analysis on the curvature of the articular cartilage or subchondral boneusing imaging tests and/or intraoperative measurements can be used todetermine the size of an area of diseased cartilage or cartilage loss.For example, the curvature can change abruptly in areas of cartilageloss. Such abrupt or sudden changes in curvature can be used to detectthe boundaries of diseased cartilage or cartilage defects.

As described above, measurements can be made while the joint isstationary, either weight bearing or not, or in motion.

II. Repair Materials

A wide variety of materials find use in the practice of the variousembodiments disclosed and described herein, including, but not limitedto, plastics, metals, crystal free metals, ceramics, biologicalmaterials (e.g., collagen or other extracellular matrix materials),hydroxyapatite, cells (e.g., stem cells, chondrocyte cells or the like),or combinations thereof. Based on the information (e.g., measurements)obtained regarding the defect and the articular surface and/or thesubchondral bone, a repair material can be formed or selected. Further,using one or more of these techniques described herein, a cartilagereplacement or regenerating material having a curvature that will fitinto a particular cartilage defect, will follow the contour and shape ofthe articular surface, and will match the thickness of the surroundingcartilage. The repair material can include any combination of materials,and typically include at least one non-pliable material, for examplematerials that are not easily bent or changed.

A. Metal and Polymeric Repair Materials

Currently, joint repair systems often employ metal and/or polymericmaterials including, for example, prostheses which are anchored into theunderlying bone (e.g., a femur in the case of a knee prosthesis). See,e.g., U.S. Pat. No. 6,203,576 to Afriat, et al. issued Mar. 20, 2001 and6,322,588 to Ogle, et al. issued Nov. 27, 2001, and references citedtherein. A wide-variety of metals are useful in the practice of thevarious embodiments, and can be selected based on any criteria. Forexample, material selection can be based on resiliency to impart adesired degree of rigidity. Non-limiting examples of suitable metalsinclude silver, gold, platinum, palladium, iridium, copper, tin, lead,antimony, bismuth, zinc, titanium, cobalt, stainless steel, nickel, ironalloys, cobalt alloys, such as Elgiloy®, a cobalt-chromium-nickel alloy,and MP35N, a nickel-cobalt-chromium-molybdenum alloy, and Nitinol™, anickel-titanium alloy, aluminum, manganese, iron, tantalum, crystal freemetals, such as Liquidmetal® alloys (available from LiquidMetalTechnologies, www.liquidmetal.com), other metals that can slowly formpolyvalent metal ions, for example to inhibit calcification of implantedsubstrates in contact with a patient's bodily fluids or tissues, andcombinations thereof.

Suitable synthetic polymers include, without limitation, polyamides(e.g., nylon), polyesters, polystyrenes, polyacrylates, vinyl polymers(e.g., polyethylene, polytetrafluoroethylene, polypropylene andpolyvinyl chloride), polycarbonates, polyurethanes, poly dimethylsiloxanes, cellulose acetates, polymethyl methacrylates, polyether etherketones, ethylene vinyl acetates, polysulfones, nitrocelluloses, similarcopolymers and mixtures thereof. Bioresorbable synthetic polymers canalso be used such as dextran, hydroxyethyl starch, derivatives ofgelatin, polyvinylpyrrolidone, polyvinyl alcohol,poly[N-(2-hydroxypropyl) methacrylamide], poly(hydroxy acids),poly(epsilon-caprolactone), polylactic acid, polyglycolic acid,poly(dimethyl glycolic acid), poly(hydroxy butyrate), and similarcopolymers can also be used.

Other materials would also be appropriate, for example, the polyketoneknown as polyetheretherketone (PEEK™). This includes the material PEEK450G, which is an unfilled PEEK approved for medical implantationavailable from Victrex of Lancashire, Great Britain. (Victrex is locatedat www.matweb.com or see Boedeker www.boedeker.com). Other sources ofthis material include Gharda located in Panoli, India(www.ghardapolymers.com).

It should be noted that the material selected can also be filled. Forexample, other grades of PEEK are also available and contemplated, suchas 30% glass-filled or 30% carbon filled, provided such materials arecleared for use in implantable devices by the FDA, or other regulatorybody. Glass filled PEEK reduces the expansion rate and increases theflexural modulus of PEEK relative to that portion which is unfilled. Theresulting product is known to be ideal for improved strength, stiffness,or stability. Carbon filled PEEK is known to enhance the compressivestrength and stiffness of PEEK and lower its expansion rate. Carbonfilled PEEK offers wear resistance and load carrying capability.

As will be appreciated, other suitable similarly biocompatiblethermoplastic or thermoplastic polycondensate materials that resistfatigue, have good memory, are flexible, and/or deflectable have verylow moisture absorption, and good wear and/or abrasion resistance, canbe used without departing from the scope of the invention. The implantcan also be comprised of polyetherketoneketone (PEKK).

Other materials that can be used include polyetherketone (PEK),polyetherketoneetherketoneketone (PEKEKK), andpolyetheretherketoneketone (PEEKK), and generally apolyaryletheretherketone. Further other polyketones can be used as wellas other thermoplastics.

Reference to appropriate polymers that can be used for the implant canbe made to the following documents, all of which are incorporated hereinby reference. These documents include: PCT Publication WO 02/02158 A1,dated Jan. 10, 2002 and entitled Bio-Compatible Polymeric Materials; PCTPublication WO 02/00275 A1, dated Jan. 3, 2002 and entitledBio-Compatible Polymeric Materials; and PCT Publication WO 02/00270 A1,dated Jan. 3, 2002 and entitled Bio-Compatible Polymeric Materials.

The polymers can be prepared by any of a variety of approaches includingconventional polymer processing methods. Various approaches include, forexample, injection molding, which is suitable for the production ofpolymer components with significant structural features, and rapidprototyping approaches, such as reaction injection molding andstereo-lithography. The substrate can be textured or made porous byeither physical abrasion or chemical alteration to facilitateincorporation of the metal coating. Other processes are alsoappropriate, such as extrusion, injection, compression molding and/ormachining techniques. Typically, the polymer is chosen for its physicaland mechanical properties and is suitable for carrying and spreading thephysical load between the joint surfaces.

More than one metal and/or polymer can be used in combination with eachother. For example, one or more metal-containing substrates can becoated with polymers in one or more regions or, alternatively, one ormore polymer-containing substrate can be coated in one or more regionswith one or more metals.

The system or prosthesis can be porous or porous coated. The poroussurface components can be made of various materials including metals,ceramics, and polymers. These surface components can, in turn, besecured by various means to a multitude of structural cores formed ofvarious metals. Suitable porous coatings include, but are not limitedto, metal, ceramic, polymeric (e.g., biologically neutral elastomerssuch as silicone rubber, polyethylene terephthalate and/or combinationsthereof) or combinations thereof. See, e.g., U.S. Pat. No. 3,605,123 toHahn, issued Sep. 20, 1971. U.S. Pat. No. 3,808,606 to Tronzo issued May7, 1974 and U.S. Pat. No. 3,843,975 to Tronzo issued Oct. 29, 1974; U.S.Pat. No. 3,314,420 to Smith issued Apr. 18, 1967; U.S. Pat. No.3,987,499 to Scharbach issued Oct. 26, 1976; and GermanOffenlegungsschrift 2,306,552. There can be more than one coating layerand the layers can have the same or different porosities. See, e.g.,U.S. Pat. No. 3,938,198 to Kahn, et al., issued Feb. 17, 1976.

The coating can be applied by surrounding a core with powdered polymerand heating until cured to form a coating with an internal network ofinterconnected pores. The tortuosity of the pores (e.g., a measure oflength to diameter of the paths through the pores) can be used inevaluating the probable success of such a coating in use on a prostheticdevice. See, also, U.S. Pat. No. 4,213,816 to Morris issued Jul. 22,1980. The porous coating can be applied in the form of a powder and thearticle as a whole subjected to an elevated temperature that bonds thepowder to the substrate. Selection of suitable polymers and/or powdercoatings can be determined in view of the teachings and references citedherein, for example based on the melt index of each.

B. Biological Repair Material

Repair materials can also include one or more biological material eitheralone or in combination with non-biological materials. For example, anybase material can be designed or shaped and suitable cartilagereplacement or regenerating material(s) such as fetal cartilage cellscan be applied to be the base. The cells can be then be grown inconjunction with the base until the thickness (and/or curvature) of thecartilage surrounding the cartilage defect has been reached. Conditionsfor growing cells (e.g., chondrocytes) on various substrates in culture,ex vivo and in vivo are described, for example, in U.S. Pat. Nos.5,478,739 to Slivka et al. issued Dec. 26, 1995; 5,842,477 to Naughtonet al. issued Dec. 1, 1998; 6,283,980 to Vibe-Hansen et al., issued Sep.4, 2001, and 6,365,405 to Salzmann et al. issued Apr. 2, 2002.Non-limiting examples of suitable substrates include plastic, tissuescaffold, a bone replacement material (e.g., a hydroxyapatite, abioresorbable material), or any other material suitable for growing acartilage replacement or regenerating material on it.

Biological polymers can be naturally occurring or produced in vitro byfermentation and the like. Suitable biological polymers include, withoutlimitation, collagen, elastin, silk, keratin, gelatin, polyamino acids,cat gut sutures, polysaccharides (e.g., cellulose and starch) andmixtures thereof. Biological polymers can be bioresorbable.

Biological materials used in the methods described herein can beautografts (from the same subject); allografts (from another individualof the same species) and/or xenografts (from another species). See,also, International Patent Publications WO 02/22014 to Alexander et al.published Mar. 21, 2002 and WO 97/27885 to Lee published Aug. 7, 1997.In certain embodiments autologous materials may be used, as they cancarry a reduced risk of immunological complications to the host,including re-absorption of the materials, inflammation and/or scarringof the tissues surrounding the implant site.

In certain embodiments, the cartilage replacement material has aparticular biochemical composition. For instance, the biochemicalcomposition of the cartilage surrounding a defect can be assessed bytaking tissue samples and chemical analysis or by imaging techniques.For example, WO 02/22014 to Alexander describes the use of gadoliniumfor imaging of articular cartilage to monitor glycosaminoglycan contentwithin the cartilage. The cartilage replacement or regenerating materialcan then be made or cultured in a manner, to achieve a biochemicalcomposition similar to that of the cartilage surrounding theimplantation site. The culture conditions used to achieve the desiredbiochemical compositions can include, for example, varyingconcentrations. Biochemical composition of the cartilage replacement orregenerating material can, for example, be influenced by controllingconcentrations and exposure times of certain nutrients and growthfactors.

In various embodiments, a container or well can be formed to theselected specifications, for example to match the material needed for aparticular subject or to create a stock of repair materials in a varietyof sizes. The size and shape of the container can be designed using thethickness and curvature information obtained from the joint and from thecartilage defect. More specifically, the inside of the container can beshaped to follow any selected measurements, for example as obtained fromthe cartilage defect(s) of a particular subject. The container can befilled with a cartilage replacement or regenerating material, forexample, collagen-containing materials, plastics, bioresorbablematerials and/or any suitable tissue scaffold. The cartilageregenerating or replacement material can also consist of a suspension ofstem cells or fetal or immature or mature cartilage cells thatsubsequently develop to more mature cartilage inside the container.Further, development and/or differentiation can be enhanced with use ofcertain tissue nutrients and growth factors.

The material is allowed to harden and/or grow inside the container untilthe material has the desired traits, for example, thickness, elasticity,hardness, biochemical composition, etc. Molds can be generated using anysuitable technique, for example computer devices and automation, e.g.computer assisted design (CAD) and, for example, computer assistedmodeling (CAM). Because the resulting material generally follows thecontour of the inside of the container it will better fit the defectitself and facilitate integration.

III. Devices Design

A. Cartilage Models

Using information on thickness and curvature of the cartilage, aphysical model of the surfaces of the articular cartilage and of theunderlying bone can be created. This physical model can berepresentative of a limited area within the joint or it can encompassthe entire joint. For example, in the knee joint, the physical model canencompass only the medial or lateral femoral condyle, both femoralcondyles and the notch region, the medial tibial plateau, the lateraltibial plateau, the entire tibial plateau, the medial patella, thelateral patella, the entire patella or the entire joint. The location ofa diseased area of cartilage can be determined, for example using a 3Dcoordinate system or a 3D Euclidian distance as described in WO02/22014.

In this way, the size of the defect to be repaired can be determined. Aswill be apparent, some, but not all, defects will include less than theentire cartilage. Thus, in one embodiment, the thickness of the normalor only mildly diseased cartilage surrounding one or more cartilagedefects is measured. This thickness measurement can be obtained at asingle point or at multiple points, for example 2 point, 4-6 points,7-10 points, more than 10 points or over the length of the entireremaining cartilage. Furthermore, once the size of the defect isdetermined, an appropriate therapy (e.g., articular repair system) canbe selected such that as much as possible of the healthy, surroundingtissue is preserved.

In other embodiments, the curvature of the articular surface can bemeasured to design and/or shape the repair material. Further, both thethickness of the remaining cartilage and the curvature of the articularsurface can be measured to design and/or shape the repair material.Alternatively, the curvature of the subchondral bone can be measured andthe resultant measurement(s) can be used to either select or shape acartilage replacement material. For example, the contour of thesubchondral bone can be used to re-create a virtual cartilage surface:the margins of an area of diseased cartilage can be identified. Thesubchondral bone shape in the diseased areas can be measured. A virtualcontour can then be created by copying the subchondral bone surface intothe cartilage surface, whereby the copy of the subchondral bone surfaceconnects the margins of the area of diseased cartilage.

Turning now to FIGS. 2 A-H, various stages of knee resurfacing steps areshown. FIG. 2 A illustrates an example of normal thickness cartilage 700in the anterior, central and posterior portion of a femoral condyle 702with a cartilage defect 705 in the posterior portion of the femoralcondyle. FIG. 2 B shows the detection of a sudden change in thicknessindicating the margins of a cartilage defect 710 that would be observedusing the imaging techniques or the mechanical, optical, laser orultrasound techniques described above. FIG. 2 C shows the margins of aweight-bearing surface 715 mapped onto the articular cartilage 700.Cartilage defect 705 is located within the weight-bearing surface 715.

FIG. 2 D shows an intended implantation site (stippled line) 720 andcartilage defect 705. In this depiction, the implantation site 720 isslightly larger than the area of diseased cartilage 705. FIG. 2 Edepicts placement of a single component articular surface repair system725. The external surface of the articular surface repair system 726 hasa curvature that seamlessly extends from the surrounding cartilage 700resulting in good postoperative alignment between the surrounding normalcartilage 700 and the articular surface repair system 725.

FIG. 2 F shows an exemplary multi-component articular surface repairsystem 730. The distal surface 733 of the second component 732 has acurvature that extends from that of the adjacent subchondral bone 735.The first component 736 has a thickness t and surface curvature 738 thatextends from the surrounding normal cartilage 700. In this embodiment,the second component 732 could be formed from a material with a Shore orRockwell hardness that is greater than the material forming the firstcomponent 736, if desired. Thus it is contemplated that the secondcomponent 732 having at least portion of the component in communicationwith the bone of the joint is harder than the first component 736 whichextends from the typically naturally softer cartilage material. Otherconfigurations, of course, are possible without departing from the scopeof the invention.

By providing a softer first component 736 and a firmer second component732, the overall implant can be configured so that its relative hardnessis analogous to that of the bone-cartilage or bone-meniscus area that itabuts. Thus, the softer material first component 736, being formed of asofter material, could perform the cushioning function of the nearbymeniscus or cartilage.

FIG. 2 G shows another single component articular surface repair system740 with a peripheral margin 745 which is configured so that it issubstantially non-perpendicular to the surrounding or adjacent normalcartilage 700. FIG. 2 H shows a multi-component articular surface repairsystem 750 with a first component 751 and a second component 752 similarto that shown in FIG. 2 G with a peripheral margin 745 of the secondcomponent 745 substantially non-perpendicular to the surrounding oradjacent normal cartilage 700.

Now turning to FIGS. 3 A-E, these figures depict exemplary knee imagingand resurfacing processes. FIG. 3 A depicts a magnified view of an areaof diseased cartilage 805 demonstrating decreased cartilage thicknesswhen compared to the surrounding normal cartilage 800. The margins 810of the defect have been determined. FIG. 3 B depicts the measurement ofcartilage thickness 815 adjacent to the defect 805. FIG. 3 C depicts theplacement of a multi-component mini-prosthesis 824 for articularresurfacing. The thickness 820 of the first component 823 closelyapproximates that of the adjacent normal cartilage 800. The thicknesscan vary in different regions of the prosthesis. The curvature of thedistal portion 824 of the first component 823 closely approximates anextension of the normal cartilage 800 surrounding the defect. Thecurvature of the distal portion 826 of the second component 825 is aprojection of the surface 827 of the adjacent subchondral bone 830 andcan have a curvature that is the same, or substantially similar, to allor part of the surrounding subchondral bone.

FIG. 3 D is a schematic depicting placement of a single componentmini-prosthesis 840 utilizing anchoring stems 845. As will beappreciated by those of skill in the art, a variety of configurations,including stems, posts, and nubs can be employed. Additionally, thecomponent is depicted such that its internal surface 829 is locatedwithin the subchondral bone 830. In an alternative construction, theinterior surface 829 conforms to the surface of the subchondral bone831.

FIG. 3 E depicts placement of a single component mini-prosthesis 840utilizing anchoring stems 845 and an opening at the external surface 850for injection of bone cement 855 or other suitable material. Theinjection material 855 can freely extravasate into the adjacent bone andmarrow space from several openings at the undersurface of themini-prosthesis 860 thereby anchoring the mini-prosthesis.

FIGS. 4 A-C, depict an alternative knee resurfacing device. FIG. 4 Adepicts a normal thickness cartilage in the anterior, central andposterior portion of a femoral condyle 900 and a large area of diseasedcartilage 905 toward the posterior portion of the femoral condyle. FIG.4 B depicts placement of a single component articular surface repairsystem 910. Again, the implantation site has been prepared with a singlecut 921, as illustrated. However, as will be appreciated by those ofskill in the art, the repair system can be perpendicular to the adjacentnormal cartilage 900 without departing from the scope of the invention.The articular surface repair system is not perpendicular to the adjacentnormal cartilage 900. FIG. 4 C depicts a multi-component articularsurface repair system 920. Again, the implantation site has beenprepared with a single cut (cut line shown as 921). The second component930 has a curvature similar to the extended surface 930 adjacentsubchondral bone 935. The first component 940 has a curvature thatextends from the adjacent cartilage 900.

B. Designs Encompassing Multiple Component Repair Materials

The articular repair system or implants described herein can include oneor more components.

FIGS. 5 A-B shows single and multiple component devices. FIG. 5 Aillustrates an example of a single component articular surface repairsystem 1400 with varying curvature and radii that fits within thesubchondral bone 1420 such that the interior surface 1402 of the system1400 does not form an extension of the surface of the subchondral bone1422. The articular surface repair system is chosen to include convex1402 and concave 1404 portions. Such devices can be utilized in alateral femoral condyle or small joints such as the elbow joint. FIG. 5B depicts a multi-component articular surface repair system with asecond component 1410 with a surface 1412 that forms an extension of thesurface 1422 of the subchondral bone 1420 and a first component 1405with an interior surface 1406 that forms an extension of the curvatureand shape of the surrounding normal cartilage 1415. The second component1410 and the first component 1405 demonstrate varying curvatures andradii with convex and concave portions that correspond to the curvatureof the subchondral bone 1420 and/or the normal cartilage 1415. As willbe appreciated by those of skill in the art, these two components can beformed such that the parts are integrally formed with each other, or canbe formed such that each part abuts the other. Additionally, therelationship between the parts can be by any suitable mechanismincluding adhesives and mechanical means.

FIGS. 6 A-B show articular repair systems 100 having an outer contour102 forming an extension of the surrounding normal cartilage 200. Thesystems are implanted into the underlying bone 300 using one or morepegs 150, 175. The pegs, pins, or screws can be porous-coated and canhave flanges 125 as shown in FIG. 5 B.

FIG. 7 shows an exemplary articular repair device 500 including a flatsurface 510 to control depth and prevent toggle; an exterior surface 515having the contour of normal cartilage; flanges 517 to prevent rotationand control toggle; a groove 520 to facilitate tissue in-growth.

FIGS. 8 A-D depict, in cross-section, another example of an implant 640with multiple anchoring pegs, stems, or screws 645. FIG. 8 B-D showvarious cross-sectional representations of various possible embodimentsof the pegs, or anchoring stems. FIG. 8 B shows a peg 645 having a notch646 or groove around its circumference; FIG. 18 C shows a peg 645 withradially-extending arms 647 that help anchor the device in theunderlying bone; and FIG. 8 D shows a peg 645 with multiple grooves orflanges 648.

FIGS. 9 A-B depict an external view of an exemplary implant 650 withmultiple anchoring pegs 655 which illustrates that the pegs are notnecessarily linearly aligned along the longitudinal axis of the device.

FIG. 10 A depicts an implant 660 with a peg 661 having radiallyextending arms 665. FIGS. 10 B-E are top views of the implant pegsillustrating a variety of suitable alternative shapes.

Examples of one-component systems include, but are not limited to, aplastic, a polymer, a metal, a metal alloy, crystal free metals, abiologic material or combinations thereof. In certain embodiments, thesurface of the repair system facing the underlying bone can be smooth.In other embodiments, the surface of the repair system facing theunderlying bone can be porous or porous-coated. In another aspect, thesurface of the repair system facing the underlying bone is designed withone or more grooves, for example to facilitate the in-growth of thesurrounding tissue. The external surface of the device can have astep-like design, which can be advantageous for altering biomechanicalstresses. Optionally, flanges can also be added at one or more positionson the device (e.g., to prevent the repair system from rotating, tocontrol toggle and/or prevent settling into the marrow cavity). Theflanges can be part of a conical or a cylindrical design. A portion orall of the repair system facing the underlying bone can also be flatwhich can help to control depth of the implant and to prevent toggle.

Non-limiting examples of multiple-component systems include combinationsof metal, plastic, metal alloys, crystal free metals, and one or morebiological materials. One or more components of the articular surfacerepair system can be composed of a biologic material (e.g. a tissuescaffold with cells such as cartilage cells or stem cells alone orseeded within a substrate such as a bioresorable material or a tissuescaffold, allograft, autograft or combinations thereof) and/or anon-biological material (e.g., polyethylene or a chromium alloy such aschromium cobalt).

Thus, the repair system can include one or more areas of a singlematerial or a combination of materials, for example, the articularsurface repair system can have a first and a second component. The firstcomponent is typically designed to have size, thickness and curvaturesimilar to that of the cartilage tissue lost while the second componentis typically designed to have a curvature similar to the subchondralbone. In addition, the first component can have biomechanical propertiessimilar to articular cartilage, including but not limited to similarelasticity and resistance to axial loading or shear forces. The firstand the second component can consist of two different metals or metalalloys. One or more components of the system (e.g., the second portion)can be composed of a biologic material including, but not limited tobone, or a non-biologic material including, but not limited tohydroxyapatite, tantalum, a chromium alloy, chromium cobalt or othermetal alloys.

One or more regions of the articular surface repair system (e.g., theouter margin of the first portion and/or the second portion) can bebioresorbable, for example to allow the interface between the articularsurface repair system and the patient's normal cartilage, over time, tobe filled in with hyaline or fibrocartilage. Similarly, one or moreregions (e.g., the outer margin of the first portion of the articularsurface repair system and/or the second portion) can be porous. Thedegree of porosity can change throughout the porous region, linearly ornon-linearly, for where the degree of porosity will typically decreasetowards the center of the articular surface repair system. The pores canbe designed for in-growth of cartilage cells, cartilage matrix, andconnective tissue thereby achieving a smooth interface between thearticular surface repair system and the surrounding cartilage.

The repair system (e.g., the second component in multiple componentsystems) can be attached to the patient's bone with use of a cement-likematerial such as methylmethacrylate, injectable hydroxy- orcalcium-apatite materials and the like.

In certain embodiments, one or more portions of the articular surfacerepair system can be pliable or liquid or deformable at the time ofimplantation and can harden later. Hardening can occur, for example,within 1 second to 2 hours (or any time period therebetween), within 1second to 30 minutes (or any time period therebetween), or between 1second and 10 minutes (or any time period therebetween).

One or more components of the articular surface repair system can beadapted to receive injections. For example, the external surface of thearticular surface repair system can have one or more openings therein.The openings can be sized to receive screws, tubing, needles or otherdevices which can be inserted and advanced to the desired depth, forexample, through the articular surface repair system into the marrowspace. Injectables such as methylmethacrylate and injectable hydroxy- orcalcium-apatite materials can then be introduced through the opening (ortubing inserted therethrough) into the marrow space thereby bonding thearticular surface repair system with the marrow space. Similarly, screwsor pins, or other anchoring mechanisms. can be inserted into theopenings and advanced to the underlying subchondral bone and the bonemarrow or epiphysis to achieve fixation of the articular surface repairsystem to the bone. Portions or all components of the screw or pin canbe bioresorbable, for example, the distal portion of a screw thatprotrudes into the marrow space can be bioresorbable. During the initialperiod after the surgery, the screw can provide the primary fixation ofthe articular surface repair system. Subsequently, ingrowth of bone intoa porous coated area along the undersurface of the articular cartilagerepair system can take over as the primary stabilizer of the articularsurface repair system against the bone.

The articular surface repair system can be anchored to the patient'sbone with use of a pin or screw or other attachment mechanism. Theattachment mechanism can be bioresorbable. The screw or pin orattachment mechanism can be inserted and advanced towards the articularsurface repair system from a non-cartilage covered portion of the boneor from a non-weight-bearing surface of the joint.

The interface between the articular surface repair system and thesurrounding normal cartilage can be at an angle, for example oriented atan angle of 90 degrees relative to the underlying subchondral bone.Suitable angles can be determined in view of the teachings herein, andin certain cases, non-90 degree angles can have advantages with regardto load distribution along the interface between the articular surfacerepair system and the surrounding normal cartilage.

The interface between the articular surface repair system and thesurrounding normal cartilage and/or bone can be covered with apharmaceutical or bioactive agent, for example a material thatstimulates the biological integration of the repair system into thenormal cartilage and/or bone. The surface area of the interface can beirregular, for example, to increase exposure of the interface topharmaceutical or bioactive agents.

C. Pre-Existing Repair Systems

As described herein, repair systems, including surgical instruments,templates, guides and/or molds, of various sizes, curvatures andthicknesses can be obtained. These repair systems, including surgicalinstruments, guides, templates and/or molds, can be catalogued andstored to create a library of systems from which an appropriate systemfor an individual patient can then be selected. In other words, adefect, or an articular surface, is assessed in a particular subject anda pre-existing repair system, including surgical instruments, templates,guides and/or molds, having a suitable shape and size is selected fromthe library for further manipulation (e.g., shaping) and implantation.

D. Mini-Prosthesis

As noted above, the methods and compositions described herein can beused to replace only a portion of the articular surface, for example, anarea of diseased cartilage or lost cartilage on the articular surface.In these systems, the articular surface repair system can be designed toreplace only the area of diseased or lost cartilage or it can extendbeyond the area of diseased or lost cartilage, e.g., 3 or 5 mm intonormal adjacent cartilage. In certain embodiments, the prosthesisreplaces less than about 70% to 80% (or any value therebetween) of thearticular surface (e.g., any given articular surface such as a singlefemoral condyle, etc.), less than about 50% to 70% (or any valuetherebetween), less than about 30% to 50% (or any value therebetween),less than about 20% to 30% (or any value therebetween), or less thanabout 20% of the articular surface.

The prosthesis can include multiple components, for example a componentthat is implanted into the bone (e.g., a metallic device) attached to acomponent that is shaped to cover the defect of the cartilage overlayingthe bone. Additional components, for example intermediate plates,meniscal repair systems and the like can also be included. It iscontemplated that each component replaces less than all of thecorresponding articular surface. However, each component need notreplace the same portion of the articular surface. In other words, theprosthesis can have a bone-implanted component that replaces less than30% of the bone and a cartilage component that replaces 60% of thecartilage. The prosthesis can include any combination, provided eachcomponent replaces less than the entire articular surface.

The articular surface repair system can be formed or selected so that itwill achieve a near anatomic fit or match with the surrounding oradjacent cartilage. Typically, the articular surface repair system isformed and/or selected so that its outer margin located at the externalsurface will be aligned with the surrounding or adjacent cartilage.

Thus, the articular repair system can be designed to replace theweight-bearing portion (or more or less than the weight bearing portion)of an articular surface, for example in a femoral condyle. Theweight-bearing surface refers to the contact area between two opposingarticular surfaces during activities of normal daily living (e.g.,normal gait). At least one or more weight-bearing portions can bereplaced in this manner, e.g., on a femoral condyle and on a tibia.

In other embodiments, an area of diseased cartilage or cartilage losscan be identified in a weight-bearing area and only a portion of theweight-bearing area, specifically the portion containing the diseasedcartilage or area of cartilage loss, can be replaced with an articularsurface repair system.

In another embodiment, the articular repair system can be designed orselected to replace substantially all of the articular surface, e.g. acondyle.

In another embodiment, for example, in patients with diffuse cartilageloss, the articular repair system can be designed to replace an areaslightly larger than the weight-bearing surface.

In certain aspects, the defect to be repaired is located only on onearticular surface, typically the most diseased surface. For example, ina patient with severe cartilage loss in the medial femoral condyle butless severe disease in the tibia, the articular surface repair systemcan only be applied to the medial femoral condyle. In the variousmethods described herein, the articular surface repair system can bedesigned to achieve an exact or a near anatomic fit with the adjacentnormal cartilage.

In other embodiments, more than one articular surface can be repaired.The area(s) of repair will be typically limited to areas of diseasedcartilage or cartilage loss or areas slightly greater than the area ofdiseased cartilage or cartilage loss within the weight-bearingsurface(s).

The implant and/or the implant site can be sculpted to achieve a nearanatomic alignment between the implant and the implant site. In anotherembodiment, an electronic image is used to measure the thickness,curvature, or shape of the articular cartilage or the subchondral bone,and/or the size of a defect, and an articular surface repair system isselected using this information. The articular surface repair system canbe inserted arthroscopically. The articular surface repair system canhave a single radius. More typically, however, as shown in FIG. 5 A,discussed above, the articular surface repair system 1400 has varyingcurvatures and radii within the same plane, e.g. anteroposterior ormediolateral or superoinferior or oblique planes, or within multipleplanes. In this manner, the articular surface repair system can beshaped to achieve a near anatomic alignment between the implant and theimplant site. This design allows not only allows for different degreesof convexity or concavity, but also for concave portions within apredominantly convex shape or vice versa 1400.

In another embodiment the articular surface repair system has ananchoring stem, used to anchor the device, for example, as described inU.S. Pat. No. 6,224,632 to Pappas et al issued May 1, 2001. The stem, orpeg, can have different shapes including conical, rectangular, fin amongothers. The mating bone cavity is typically similarly shaped as thecorresponding stem.

As shown in FIG. 6, discussed above, the articular surface repair system100 can be affixed to the subchondral bone 300, with one or more stems,or pegs, 150 extending through the subchondral plate into the marrowspace. In certain instances, this design can reduce the likelihood thatthe implant will settle deeper into the joint over time by restingportions of the implant against the subchondral bone. The stems, orpegs, can be of any shape suitable to perform the function of anchoringthe device to the bone. For example, the pegs can be cylindrical orconical. Optionally, the stems, or pegs, can further include notches oropenings to allow bone in-growth. In addition, the stems can be porouscoated for bone in-growth. The anchoring stems or pegs can be affixed tothe bone using bone cement. An additional anchoring device can also beaffixed to the stem or peg. The anchoring device can have an umbrellashape (e.g., radially expanding elements) with the wider portionpointing towards the subchondral bone and away from the peg. Theanchoring device can be advantageous for providing immediate fixation ofthe implant. The undersurface of the articular repair system facing thesubchondral bone can be textured or rough thereby increasing the contactsurface between the articular repair system and the subchondral bone.Alternatively, the undersurface of the articular repair system can beporous coated thereby allowing in-growth. The surgeon can support thein-growth of bone by treating the subchondral bone with a rasp,typically to create a larger surface area and/or until bleeding from thesubchondral bone occurs.

In another embodiment, the articular surface repair system can beattached to the underlying bone or bone marrow using bone cement. Bonecement is typically made from an acrylic polymeric material. Typically,the bone cement is comprised of two components: a dry powder componentand a liquid component, which are subsequently mixed together. The drycomponent generally includes an acrylic polymer, such aspolymethylmethacrylate (PMMA). The dry component can also contain apolymerization initiator such as benzoylperoxide, which initiates thefree-radical polymerization process that occurs when the bone cement isformed. The liquid component, on the other hand, generally contains aliquid monomer such as methyl methacrylate (MMA). The liquid componentcan also contain an accelerator such as an amine (e.g.,N,N-dimethyl-p-toluidine). A stabilizer, such as hydroquinone, can alsobe added to the liquid component to prevent premature polymerization ofthe liquid monomer. When the liquid component is mixed with the drycomponent, the dry component begins to dissolve or swell in the liquidmonomer. The amine accelerator reacts with the initiator to form freeradicals that begin to link monomer units to form polymer chains. In thenext two to four minutes, the polymerization process proceeds changingthe viscosity of the mixture from a syrup-like consistency (lowviscosity) into a dough-like consistency (high viscosity). Ultimately,further polymerization and curing occur, causing the cement to hardenand affix a prosthesis to a bone.

In certain aspects of the embodiments disclosed herein, bone cement oranother liquid attachment material such as injectablecalciumhydroxyapatite can be injected into the marrow cavity through oneor more openings in the prosthesis. These openings in the prosthesiscould extend from the articular surface to the undersurface of theprosthesis. After injection, the openings could be closed with apolymer, silicon, metal, metal alloy or bioresorbable plug.

In another embodiment, one or more components of the articular surfacerepair (e.g., the surface of the system that is pointing towards theunderlying bone or bone marrow) can be porous or porous coated. Avariety of different porous metal coatings have been proposed forenhancing fixation of a metallic prosthesis by bone tissue in-growth.Thus, for example, U.S. Pat. No. 3,855,638 to Pilliar issued Dec. 24,2974, discloses a surgical prosthetic device, which can be used as abone prosthesis, comprising a composite structure consisting of a solidmetallic material substrate and a porous coating of the same solidmetallic material adhered to and extending over at least a portion ofthe surface of the substrate. The porous coating consists of a pluralityof small discrete particles of metallic material bonded together attheir points of contact with each other to define a plurality ofconnected interstitial pores in the coating. The size and spacing of theparticles, which can be distributed in a plurality of monolayers, can besuch that the average interstitial pore size is not more than about 200microns. Additionally, the pore size distribution can be substantiallyuniform from the substrate-coating interface to the surface of thecoating. In another embodiment, the articular surface repair system cancontain one or more polymeric materials that can be loaded with andrelease therapeutic agents including drugs or other pharmacologicaltreatments that can be used for drug delivery. The polymeric materialscan, for example, be placed inside areas of porous coating. Thepolymeric materials can be used to release therapeutic drugs, e.g. boneor cartilage growth stimulating drugs. This embodiment can be combinedwith other embodiments, wherein portions of the articular surface repairsystem can be bioresorbable. For example, the first layer of anarticular surface repair system or portions of its first layer can bebioresorbable. As the first layer gets increasingly resorbed, localrelease of a cartilage growth-stimulating drug can facilitate in-growthof cartilage cells and matrix formation.

In any of the methods or compositions described herein, the articularsurface repair system can be pre-manufactured with a range of sizes,curvatures and thicknesses. Alternatively, the articular surface repairsystem can be custom-made for an individual patient. In addition, therepair system can incorporate various anatomical relief features, asdescribed below, to accommodate various anatomical features of thepatient.

IV. Manufacturing

A. Shaping

In certain instances shaping of the repair material will be requiredbefore or after formation (e.g., growth to desired thickness or afterselection of a pre-manufactured implant and/or blank), for example wherethe thickness of the required cartilage material is not uniform (e.g.,where different sections of the cartilage replacement or regeneratingmaterial require different thicknesses). Shaping can include the removalof material as well as the addition of material, as well as combinationsthereof for differing areas of a single implant.

The replacement material can be shaped by any suitable techniqueincluding, but not limited to, mechanical abrasion, laser abrasion orablation, radiofrequency treatment, cryoablation, metal additivetechnologies, variations in exposure time and concentration ofnutrients, enzymes or growth factors and any other means suitable forinfluencing or changing cartilage thickness. See, e.g., WO 00/15153 toMansmann published Mar. 23, 2000; If enzymatic digestion is used,certain sections of the cartilage replacement or regenerating materialcan be exposed to higher doses of the enzyme or can be exposed longer asa means of achieving different thicknesses and curvatures of thecartilage replacement or regenerating material in different sections ofsaid material.

The material can be shaped manually and/or automatically, for exampleusing a device into which a pre-selected thickness and/or curvature hasbeen input and then programming the device using the input informationto achieve the desired shape.

In addition to, or instead of, shaping the cartilage repair material,the site of implantation (e.g., bone surface, any cartilage materialremaining, etc.) can also be shaped by any suitable technique in orderto enhance integration of the repair material.

B. Sizing

The articular repair system can be formed or selected so that it willachieve a near anatomic fit or match with the surrounding or adjacentcartilage or subchondral bone or menisci and other tissue. The shape ofthe repair system can be based on the analysis of an electronic image(e.g. MRI, CT, digital tomosynthesis, optical coherence tomography orthe like). If the articular repair system is intended to replace an areaof diseased cartilage or lost cartilage, the near anatomic fit can beachieved using a method that provides a virtual reconstruction of theshape of healthy cartilage in an electronic image.

In one embodiment, a near normal cartilage surface at the position ofthe cartilage defect can be reconstructed by interpolating the healthycartilage surface across the cartilage defect or area of diseasedcartilage. This can, for example, be achieved by describing the healthycartilage by means of a parametric surface (e.g. a B-spline surface),for which the control points are placed such that the parametric surfacefollows the contour of the healthy cartilage and bridges the cartilagedefect or area of diseased cartilage. The continuity properties of theparametric surface will provide a smooth integration of the part thatbridges the cartilage defect or area of diseased cartilage with thecontour of the surrounding healthy cartilage. The part of the parametricsurface over the area of the cartilage defect or area of diseasedcartilage can be used to determine the shape or part of the shape of thearticular repair system to match with the surrounding cartilage.

In another embodiment, a near normal cartilage surface at the positionof the cartilage defect or area of diseased cartilage can bereconstructed using morphological image processing. In a first step, thecartilage can be extracted from the electronic image using manual,semi-automated and/or automated segmentation techniques (e.g., manualtracing, region growing, live wire, model-based segmentation), resultingin a binary image. Defects in the cartilage appear as indentations thatcan be filled with a morphological closing operation performed in 2-D or3-D with an appropriately selected structuring element. The closingoperation is typically defined as a dilation followed by an erosion. Adilation operator sets the current pixel in the output image to 1 if atleast one pixel of the structuring element lies inside a region in thesource image. An erosion operator sets the current pixel in the outputimage to 1 if the whole structuring element lies inside a region in thesource image. The filling of the cartilage defect or area of diseasedcartilage creates a new surface over the area of the cartilage defect orarea of diseased cartilage that can be used to determine the shape orpart of the shape of the articular repair system to match with thesurrounding cartilage or subchondral bone.

As described above, the articular repair system, including surgicaltools and instruments, molds, in situ repair systems, etc. can be formedor selected from a library or database of systems of various sizes,curvatures and thicknesses so that it will achieve a near anatomic fitor match with the surrounding or adjacent cartilage and/or subchondralbone. These systems can be pre-made or made to order for an individualpatient. In order to control the fit or match of the articular repairsystem with the surrounding or adjacent cartilage or subchondral bone ormenisci and other tissues preoperatively, a software program can be usedthat projects the articular repair system over the anatomic positionwhere it will be implanted. Suitable software is commercially availableand/or readily modified or designed by a skilled programmer.

In yet another embodiment, the articular repair system includingunicompartmental and total knee implants as well as hip devices can beprojected over the implantation site using one or more 2-D or 3-Dimages. The cartilage and/or subchondral bone and other anatomicstructures can be optionally extracted from a 2-D or 3-D electronicimage such as an MRI or a CT using manual, semi-automated and/orautomated segmentation techniques. A 2-D or 3-D representation of thecartilage and/or bone and other anatomic structures as well as thearticular repair system can be generated, for example using a polygon orNURBS surface or other parametric surface representation. Ligaments,menisci and other articular structures can be displayed in 2-D and 3-D.For a description of various parametric surface representations see, forexample Foley, J. D. et al., Computer Graphics Principles and Practicein C; Addison-Wesley, 2^(nd) edition, 1995).

The 2-D or 3-D representations of the cartilage and/or subchondral boneand other anatomic structures and the articular repair system can bemerged into a common coordinate system. The articular repair system,including surgical tools and instruments, molds, in situ repair systems,etc. can then be placed at the desired implantation site. Therepresentations of the cartilage, subchondral bone, ligaments, menisciand other anatomic structures and the articular repair system arerendered into a 2-D or 3-D image, for example application programminginterfaces (APIs) OpenGL® (standard library of advanced 3-D graphicsfunctions developed by SGI, Inc.; available as part of the drivers forPC-based video cards, for example from www.nvidia.com for NVIDIA videocards or www.3dlabs.com for 3Dlabs products, or as part of the systemsoftware for Unix workstations) or DirectX® (multimedia API forMicrosoft Windows® based PC systems; available from www.microsoft.com).The 2-D or 3-D image can be rendered or displayed showing the cartilage,subchondral bone, ligaments, menisci or other anatomic objects, and thearticular repair system from varying angles, e.g. by rotating or movingthem interactively or non-interactively, in real-time or non-real-time.

In another embodiment, the implantation site may be visualized using oneor more cross-sectional 2-D images, as described in U.S. Ser. No.10/305,652, entitled “Methods and Compositions for Articular Repair,”filed Nov. 27, 2002, which is hereby incorporated by reference in itsentirety. Typically, a series of 2-D cross-sectional images will beused. The 2-D images can be generated with imaging tests such as CT,MRI, digital tomosynthesis, ultrasound, optical imaging, opticalcoherence tomography, other imaging modalities using methods and toolsknown to those of skill in the art. The articular repair system orimplant can then be superimposed onto one or more of these 2-D images.The 2-D cross-sectional images may be reconstructed in other planes,e.g. from sagittal to coronal, etc. Isotropic data sets (e.g., data setswhere the slice thickness is the same or nearly the same as the in-planeresolution) or near isotropic data sets can also be used. Multipleplanes may be displayed simultaneously, for example using a split screendisplay. The operator may also scroll through the 2-D images in anydesired orientation in real time or near real time; the operator canrotate the imaged tissue volume while doing this. The articular repairsystem or implant may be displayed in cross-section utilizing differentdisplay planes, e.g. sagittal, coronal or axial, typically matchingthose of the 2-D images demonstrating the cartilage, subchondral bone,ligaments, menisci or other tissue. Alternatively, a three-dimensionaldisplay may be used for the articular repair system. The 2-D electronicimage and the 2-D or 3-D representation of the articular repair systemor implant may be merged into a common coordinate system. The cartilagerepair system or implant can then be placed at the desired implantationsite. The series of 2-D cross-sections of the anatomic structures, theimplantation site and the articular repair system or implant may bedisplayed interactively (e.g. the operator can scroll through a seriesof slices) or non-interactively (e.g. as an animation that moves throughthe series of slices), in real-time or non-real-time.

The software can be designed so that the articular repair system,including surgical tools and instruments, molds, in situ repair systems,etc. with the best fit relative to the cartilage and/or subchondral boneis automatically selected, for example using one or more of thetechniques described above. Alternatively, the operator can select anarticular repair system, including surgical tools and instruments,molds, in situ repair systems, etc. and project it or drag it onto theimplantation site displayed on the cross-sectional 2-D or the 3-Dimages. The operator can then move and rotate the articular repairsystem relative to the implantation site and scroll through across-sectional 2-D or 3-D display of the articular repair system and ofthe anatomic structures. The operator can perform a visual and/orcomputer-assisted inspection of the fit between the articular repairsystem and the implantation site. This can be performed for differentpositions of the joint, e.g. extension, 45, 90 degrees of flexion,adduction, abduction, internal or external rotation. The procedure canbe repeated until a satisfactory fit has been achieved. The procedurecan be entirely manual by the operator; it can, however, also becomputer-assisted. For example, the software can select a first trialimplant that the operator can test (e.g., evaluate the fit). Softwarethat highlights areas of poor alignment between the implant and thesurrounding cartilage or subchondral bone or menisci or other tissuescan also be designed and used. Based on this information, the softwareor the operator can select another implant and test its alignment.

In all of the above embodiments, the biomechanical axis and relevantanatomical axes or planes can be displayed simultaneous with the jointand/or articular repair device in the 2-D or 3-D display. Simultaneousdisplay of at least one or more biomechanical axes or anatomical axes orplanes can help improve the assessment of fit of the articular repairsystem. Biomechanical axis or relevant anatomical axes or planes canalso be displayed for different positions of the joint.

C. Rapid Prototyping, Other Manufacturing Techniques

Rapid prototyping is a technique for fabricating a three-dimensionalobject from a computer model of the object. A special printer is used tofabricate the prototype from a plurality of two-dimensional layers.Computer software sections the representations of the object into aplurality of distinct two-dimensional layers and then athree-dimensional printer fabricates a layer of material for each layersectioned by the software. Together the various fabricated layers formthe desired prototype. More information about rapid prototypingtechniques is available in US Patent Publication No 200210079601A1 toRussell et al., published Jun. 27, 2002. An advantage to using rapidprototyping is that it enables the use of free form fabricationtechniques that use toxic or potent compounds safely. These compoundscan be safely incorporated in an excipient envelope, which reducesworker exposure

A powder piston and build bed can be provided. Powder includes anymaterial (metal, plastic, etc.) that can be made into a powder or bondedwith a liquid. The power is rolled from a feeder source with a spreaderonto a surface of a bed. The thickness of the layer is controlled by thecomputer. The print head then deposits a binder fluid onto the powderlayer at a location where it is desired that the powder bind. Powder isagain rolled into the build bed and the process is repeated, with thebinding fluid deposition being controlled at each layer to correspond tothe three-dimensional location of the device formation. For a furtherdiscussion of this process see, for example, US Patent Publication No2003/017365A1 to Monkhouse et al. published Sep. 18, 2003.

The rapid prototyping can use the two dimensional images obtained todetermine each of the two-dimensional shapes for each of the layers ofthe prototyping machine. In this scenario, each two dimensional imageslice would correspond to a two dimensional prototype slide.Alternatively, the three-dimensional shape of the defect can bedetermined, as described above, and then broken down into twodimensional slices for the rapid prototyping process. The advantage ofusing the three-dimensional model is that the two-dimensional slicesused for the rapid prototyping machine can be along the same plane asthe two-dimensional images taken or along a different plane altogether.

Rapid prototyping can be combined or used in conjunction with castingtechniques. For example, a shell or container with inner dimensionscorresponding to an articular repair system including surgicalinstruments, molds, alignment guides or surgical guides, can be madeusing rapid prototyping. Plastic or wax-like materials are typicallyused for this purpose. The inside of the container can subsequently becoated, for example with a ceramic, for subsequent casting. Using thisprocess, personalized casts can be generated.

Rapid prototyping can be used for producing articular repair systemsincluding surgical tools, molds, alignment guides, cut guides etc. Rapidprototyping can be performed at a manufacturing facility. Alternatively,it may be performed in the operating room after an intraoperativemeasurement has been performed.

Alternatively, milling techniques can be utilized for producingarticular repair systems including surgical tools, molds, alignmentguides, cut guides etc.

Alternatively, laser based techniques can be utilized for producingarticular repair systems including surgical tools, molds, alignmentguides, cut guides etc.

V. Implantation

Following one or more manipulations (e.g., shaping, growth, development,etc), the cartilage replacement or regenerating material can then beimplanted into the area of the defect. Implantation can be performedwith the cartilage replacement or regenerating material still attachedto the base material or removed from the base material. Any suitablemethods and devices can be used for implantation, for example, devicesas described in U.S. Pat. Nos. 6,375,658 to Hangody et al. issued Apr.23, 2002; 6,358,253 to Torrie et al. issued Mar. 19, 2002; 6,328,765 toHardwick et al. issued Dec. 11, 2001; and International Publication WO01/19254 to Cummings et al. published Mar. 22, 2001.

In selected cartilage defects, the implantation site can be preparedwith a single cut across the articular surface, for example, as shown inFIG. 8. In this case, single 810 and multi-component 820 prostheses canbe utilized.

A. The Joint Replacement Procedure

i. Knee Joint

Performing a total knee arthroplasty is a complicated procedure. Inreplacing the knee with an artificial knee, it is often desirable to getthe anatomical and mechanical axes of the lower extremity alignedcorrectly to ensure optimal functioning of the implanted knee.

As shown in FIG. 11A, the center of the hip 1902 (located at the head1930 of the femur 1932), the center of the knee 1904 (located at thenotch where the intercondylar tubercle 1934 of the tibia 1936 meet thefemur) and ankle 1906 lie approximately in a straight line 1910 whichdefines the mechanical axis of the lower extremity. The anatomic axis1920 aligns 5-7° offset θ from the mechanical axis in the valgus, oroutward, direction.

The long axis of the tibia 1936 is collinear with the mechanical axis ofthe lower extremity 1910. From a three-dimensional perspective, thelower extremity of the body ideally functions within a single planeknown as the median anterior-posterior plane (MAP-plane) throughout theflexion-extension arc. In order to accomplish this, the femoral head1930, the mechanical axis of the femur, the patellar groove, theintercondylar notch, the patellar articular crest, the tibia and theankle remain within the MAP-plane during the flexion-extension movement.During movement, the tibia rotates as the knee flexes and extends in theepicondylar axis which is perpendicular to the MAP-plane.

A variety of image slices can be taken at each individual joint, e.g.,the knee joint 1950-1950 _(n), and the hip joint 1952-1950 _(n). Theseimage slices can be used as described above in Section I along with animage of the full leg to ascertain the axis.

With disease and malfunction of the knee, alignment of the anatomic axisis altered. Performing a total knee arthroplasty is one solution forcorrecting a diseased knee. Implanting a total knee joint, such as thePFC Sigma RP Knee System by Johnson & Johnson, requires that a series ofresections be made to the surfaces forming the knee joint in order tofacilitate installation of the artificial knee. The resections should bemade to enable the installed artificial knee to achieveflexion-extension movement within the MAP-plane and to optimize thepatient's anatomical and mechanical axis of the lower extremity.

First, the tibia 1930 is resected to create a flat surface to accept thetibial component of the implant. In most cases, the tibial surface isresected perpendicular to the long axis of the tibia in the coronalplane, but is typically sloped 4-7° posteriorly in the sagittal plane tomatch the normal slope of the tibia. As will be appreciated by those ofskill in the art, the sagittal slope can be 0° where the device to beimplanted does not require a sloped tibial cut. The resection line 1958is perpendicular to the mechanical axis 1910, but the angle between theresection line and the surface plane of the plateau 1960 variesdepending on the amount of damage to the knee.

FIGS. 11 B-D illustrate an anterior view of a resection of ananatomically normal tibial component, a tibial component in a varusknee, and a tibial component in a valgus knee, respectively. In eachfigure, the mechanical axis 1910 extends vertically through the bone andthe resection line 1958 is perpendicular to the mechanical axis 1910 inthe coronal plane, varying from the surface line formed by the jointdepending on the amount of damage to the joint. FIG. 11 B illustrates anormal knee wherein the line corresponding to the surface of the joint1960 is parallel to the resection line 1958. FIG. 11 C illustrates avarus knee wherein the line corresponding to the surface of the joint1960 is not parallel to the resection line 1958. FIG. 11 D illustrates avalgus knee wherein the line corresponding to the surface of the joint1960 is not parallel to the resection line 1958.

Once the tibial surface has been prepared, the surgeon turns topreparing the femoral condyle.

The plateau of the femur 1970 is resected to provide flat surfaces thatcommunicate with the interior of the femoral prosthesis. The cuts madeto the femur are based on the overall height of the gap to be createdbetween the tibia and the femur. Typically, a 20 mm gap is desirable toprovide the implanted prosthesis adequate room to achieve full range ofmotion. The bone is resected at a 5-7° angle valgus to the mechanicalaxis of the femur. Resected surface 1972 forms a flat plane with anangular relationship to adjoining surfaces 1974, 1976. The angle θ′, θ″between the surfaces 1972-1974, and 1972-1976 varies according to thedesign of the implant.

ii. Hip Joint

As illustrated in FIG. 11F, the external geometry of the proximal femurincludes the head 1980, the neck 1982, the lesser trochanter 1984, thegreater trochanter 1986 and the proximal femoral diaphysis. The relativepositions of the trochanters 1984, 1986, the femoral head center 1902and the femoral shaft 1988 are correlated with the inclination of theneck-shaft angle. The mechanical axis 1910 and anatomic axis 1920 arealso shown. Assessment of these relationships can change the reamingdirection to achieve neutral alignment of the prosthesis with thefemoral canal.

Using anteroposterior and lateral radiographs, measurements are made ofthe proximal and distal geometry to determine the size and optimaldesign of the implant.

Typically, after obtaining surgical access to the hip joint, the femoralneck 1982 is resected, e.g. along the line 1990. Once the neck isresected, the medullary canal is reamed. Reaming can be accomplished,for example, with a conical or straight reamer, or a flexible reamer.The depth of reaming is dictated by the specific design of the implant.Once the canal has been reamed, the proximal reamer is prepared byserial rasping, with the rasp directed down into the canal.

B. Surgical Tools

Further, surgical assistance can be provided by using a device appliedto the outer surface of the articular cartilage or the bone, includingthe subchondral bone, in order to match the alignment of the articularrepair system and the recipient site or the joint. The device can beround, circular, oval, ellipsoid, curved or irregular in shape. Theshape can be selected or adjusted to match or enclose an area ofdiseased cartilage or an area slightly larger than the area of diseasedcartilage or substantially larger than the diseased cartilage. The areacan encompass the entire articular surface or the weight bearingsurface. Such devices can be used when replacement of a majority or anentire articular surface is contemplated.

Mechanical devices can be used for surgical assistance (e.g., surgicaltools), for example using gels, molds, plastics or metal. One or moreelectronic images or intraoperative measurements can be obtainedproviding object coordinates that define the articular and/or bonesurface and shape. These objects' coordinates can be utilized to eithershape the device, e.g. using a CAD/CAM technique, to be adapted to apatient's articular anatomy or, alternatively, to select a typicallypre-made device that has a good fit with a patient's articular anatomy.The device can have a surface and shape that will match all or portionsof the articular cartilage, subchondral bone and/or other bone surfaceand shape, e.g. similar to a “mirror image.” The device can include,without limitation, one or more cut planes, apertures, slots and/orholes to accommodate surgical instruments such as drills, reamers,curettes, k-wires, screws and saws.

The device may have a single component or multiple components. Thecomponents may be attached to the unoperated and operated portions ofthe intra- or extra-articular anatomy. For example, one component may beattached to the femoral neck, while another component may be in contactwith the greater or lesser trochanter. Typically, the differentcomponents can be used to assist with different parts of the surgicalprocedure. When multiple components are used, one or more components mayalso be attached to a different component rather than the articularcartilage, subchondral bone or other areas of osseous or non-osseousanatomy. For example, a tibial mold may be attached to a femoral moldand tibial cuts can be performed in reference to femoral cuts.

Components may also be designed to fit to the joint after an operativestep has been performed. For example, in a knee, one component may bedesigned to fit all or portions of a distal femur before any cuts havebeen made, while another component may be designed to fit on a cut thathas been made with the previously used mold or component. In a hip, onecomponent may be used to perform an initial cut, for example through thefemoral neck, while another subsequently used component may be designedto fit on the femoral neck after the cut, for example covering the areaof the cut with a central opening for insertion of a reamer. Using thisapproach, subsequent surgical steps may also be performed with highaccuracy, e.g. reaming of the marrow cavity.

In another embodiment, a guide may be attached to a mold to control thedirection and orientation of surgical instruments. For example, afterthe femoral neck has been cut, a mold may be attached to the area of thecut, whereby it fits portions or all of the exposed bone surface. Themold may have an opening adapted for a reamer. Before the reamer isintroduced a femoral reamer guide may be inserted into the mold andadvanced into the marrow cavity. The position and orientation of thereamer guide may be determined by the femoral mold. The reamer can thenbe advanced over the reamer guide and the marrow cavity can be reamedwith improved accuracy. Similar approaches are feasible in the knee andother joints.

All mold components may be disposable. Alternatively, some moldscomponents may be re-usable. Typically, mold components applied after asurgical step such as a cut as been performed can be reusable, since areproducible anatomic interface will have been established.

Interconnecting or bridging components may be used. For example, suchinterconnecting or bridging components may couple the mold attached tothe joint with a standard, unmodified or only minimally modified cutblock used during knee or hip surgery. Interconnecting or bridgingcomponents may be made of plastic or metal. When made of metal or otherhard material, they can help protect the joint from plastic debris, forexample when a reamer or saw would otherwise get into contact with themold.

The accuracy of the attachment between the component or mold and thecartilage or subchondral bone or other osseous structures can be betterthan 2 mm, better than 1 mm, better than 0.7 mm, better than 0.5 mm, orbetter than 0.5 mm. The accuracy of the attachment between differentcomponents or between one or more molds and one or more surgicalinstruments can be better than 2 mm, better than 1 mm, better than 0.7mm, better than 0.5 mm, or better than 0.5 mm.

The angular error of any attachments or between any components orbetween components, molds, instruments and/or the anatomic orbiomechanical axes is less than 2 degrees, less than 1.5 degrees, lessthan 1 degree, and/or less than 0.5 degrees. The total angular error canbe less than 2 degrees, less than 1.5 degrees, less than 1 degree,and/or less than 0.5 degrees.

In various embodiments, a position will be chosen that will result in ananatomically desirable cut plane, drill hole, or general instrumentorientation for subsequent placement of an articular repair system orfor facilitating placement of the articular repair system. Moreover, thedevice can be designed so that the depth of the drill, reamer or othersurgical instrument can be controlled, e.g., the drill cannot go anydeeper into the tissue than defined by the device, and the size of thehole in the block can be designed to essentially match the size of theimplant. Information about other joints or axis and alignmentinformation of a joint or extremity can be included when selecting theposition of these slots or holes. Alternatively, the openings in thedevice can be made larger than needed to accommodate these instruments.The device can also be configured to conform to the articular shape. Theapertures, or openings, provided can be wide enough to allow for varyingthe position or angle of the surgical instrument, e.g., reamers, saws,drills, curettes and other surgical instruments. An instrument guide,typically comprised of a relatively hard material, can then be appliedto the device. The device helps orient the instrument guide relative tothe three-dimensional anatomy of the joint.

The mold may contact the entire articular surface. In variousembodiments, the mold can be in contact with only a portion of thearticular surface. Thus, the mold can be in contact, without limitation,with: 100% of the articular surface; 80% of the articular surface; 50%of the articular surface; 30% of the articular surface; 30% of thearticular surface; 20% of the articular surface; or 10% or less of thearticular surface. An advantage of a smaller surface contact area is areduction in size of the mold thereby enabling cost efficientmanufacturing as well as predisposing the implant for implantation usingminimally invasive surgical techniques. The size of the mold and itssurface contact areas should be sufficient, however, to ensure accurateplacement so that subsequent drilling and cutting can be performed withsufficient accuracy.

In various embodiments, the maximum diameter of the mold is less than 10cm. In other embodiments, the maximum diameter of the mold may be lessthan: 8 cm; 5 cm; 4 cm; 3 cm; or even less than 2 cm.

The mold may be in contact with three or more surface points rather thanan entire surface. These surface points may be on the articular surfaceor external to the articular surface. By using contact points ratherthan an entire surface or portions of the surface, the size of the moldmay be reduced.

Reductions in the size of the mold can be used to enable minimallyinvasive surgery (MIS) in the hip, the knee, the shoulder and otherjoints. MIS technique with small molds will help to reduceintraoperative blood loss, preserve tissue including possibly bone,enable muscle sparing techniques and reduce postoperative pain andenable faster recovery. Thus, in one embodiment, the mold is used inconjunction with a muscle sparing technique. In another embodiment, themold may be used with a bone sparing technique. In another embodiment,the mold is shaped to enable MIS technique with an incision size of lessthan 15 cm, or less than 13 cm, or less than 10 cm, or less than 8 cm,or less than 6 cm.

The mold may be placed in contact with points or surfaces outside of thearticular surface. For example, the mold can rest on bone in theintercondylar notch or the anterior or other aspects of the tibia or theacetabular rim or the lesser or greater trochanter. Optionally, the moldmay only rest on points or surfaces that are external to the articularsurface. Furthermore, the mold may rest on points or surfaces within theweight-bearing surface, or on points or surfaces external to theweight-bearing surface.

The mold may be designed to rest on bone or cartilage outside the areato be worked on, e.g. cut, drilled etc. In this manner, multiplesurgical steps can be performed using the same mold. For example, in theknee, the mold may be stabilized against portions of the intercondylarnotch, which can be selected external to areas to be removed for totalknee arthroplasty or other procedures. In the hip, the mold may beattached external to the acetabular fossa, providing a reproduciblereference that is maintained during a procedure, for example total hiparthroplasty. The mold may be affixed to the underlying bone, forexample with pins or drills etc.

In additional embodiments, the mold may rest on the articular cartilage.The mold may rest on the subchondral bone or on structures external tothe articular surface that are within the joint space or on structuresexternal to the joint space. If the mold is designed to rest on thecartilage, an imaging test demonstrating the articular cartilage can beused in one embodiment. This can, for example, include ultrasound,spiral CT arthrography, MRI using, for example, cartilage displayingpulse sequences, or MRI arthrography. In another embodiment, an imagingtest demonstrating the subchondral bone, e.g. CT or spiral CT, can beused and a standard cartilage thickness can be added to the scan. Thestandard cartilage thickness can be derived, for example, using ananatomic reference database, age, gender, and race matching, ageadjustments and any method known in the art or developed in the futurefor deriving estimates of cartilage thickness. The standard cartilagethickness may, in some embodiments, be uniform across one or morearticular surfaces or it can change across the articular surface.

The mold may be adapted to rest substantially on subchondral bone. Inthis case, residual cartilage can create some offset and inaccurateresult with resultant inaccuracy in surgical cuts, drilling and thelike. In various embodiments, portions of the residual cartilage can beremoved in a first step in areas where the mold is designed to contactthe bone and the subchondral bone is exposed. In a second step, the moldis then placed on the subchondral bone.

With advanced osteoarthritis, significant articular deformity canresult. The articular surface(s) can become flattened. There can be cystformation or osteophyte formation. “Tram track” like structures can formon the articular surface. In one embodiment, osteophytes or otherdeformities may be removed by the computer software prior to generationof the mold. The software can automatically, semi-automatically ormanually with input from the user simulate surgical removal of theosteophytes or other deformities, and predict the resulting shape of thejoint and the associated surfaces. The mold can then be designed basedon the predicted shape. Intraoperatively, these osteophytes or otherdeformities can then also optionally be removed prior to placing themold and performing the procedure. Alternatively, the mold can bedesigned to avoid such deformities, such as by incorporating one or moreanatomical relief surfaces. For example, the mold may only be in contactwith points on the articular surface or external to the articularsurface that are not affected or involved by osteophytes. The mold canrest on the articular surface or external to the articular surface onthree or more points or small surfaces with the body of the moldelevated or detached from the articular surface so that the accuracy ofits position cannot be affected by osteophytes or other articulardeformities. The mold can rest on one or more tibial spines or portionsof the tibial spines. Alternatively, all or portions of the mold may bedesigned to rest on osteophytes or other excrescences or pathologicalchanges.

The surgeon can, optionally, make fine adjustments between the alignmentdevice and the instrument guide. In this manner, an optimal compromisecan be found, for example, between biomechanical alignment and jointlaxity or biomechanical alignment and joint function, e.g. in a kneejoint flexion gap and extension gap. By oversizing the openings in thealignment guide, the surgeon can utilize the instruments and insert themin the instrument guide without damaging the alignment guide. Thus, inparticular if the alignment guide is made of plastic, debris will not beintroduced into the joint. The position and orientation between thealignment guide and the instrument guide can be also be optimized withthe use of, for example, interposed spacers, wedges, screws and othermechanical or electrical methods known in the art.

A surgeon may desire to influence joint laxity as well as jointalignment. This can be optimized for different flexion and extension,abduction, or adduction, internal and external rotation angles. For thispurpose, for example, spacers can be introduced that are attached orthat are in contact with one or more molds. The surgeon canintraoperatively evaluate the laxity or tightness of a joint usingspacers with different thickness or one or more spacers with the samethickness. For example, spacers can be applied in a knee joint in thepresence of one or more molds and the flexion gap can be evaluated withthe knee joint in flexion. The knee joint can then be extended and theextension gap can be evaluated. Ultimately, the surgeon will select anoptimal combination of spacers for a given joint and mold. A surgicalcut guide can be applied to the mold with the spacers optionallyinterposed between the mold and the cut guide. In this manner, the exactposition of the surgical cuts can be influenced and can be adjusted toachieve an optimal result. Thus, the position of a mold can be optimizedrelative to the joint, bone or cartilage for soft-tissue tension,ligament balancing or for flexion, extension, rotation, abduction,adduction, anteversion, retroversion and other joint or bone positionsand motion. The position of a cut block or other surgical instrument maybe optimized relative to the mold for soft-tissue tension or forligament balancing or for flexion, extension, rotation, abduction,adduction, anteversion, retroversion and other joint or bone positionsand motion. Both the position of the mold and the position of othercomponents including cut blocks and surgical instruments may beoptimized for soft-tissue tension or for ligament balancing or forflexion, extension, rotation, abduction, adduction, anteversion,retroversion and other joint or bone positions and motion.

Someone skilled in the art will recognize other means for optimizing theposition of the surgical cuts or other interventions. As stated above,expandable or ratchet-like devices may be utilized that can be insertedinto the joint or that can be attached or that can touch the mold (seealso FIG. 27 D). Such devices can extend from a cutting block or otherdevices attached to the mold, optimizing the position of drill holes orcuts for different joint positions or they can be integrated inside themold. Integration in the cutting block or other devices attached to themold is contemplated, since the expandable or ratchet-like mechanismscan be sterilized and re-used during other surgeries, for example inother patients. Optionally, the expandable or ratchet-like devices maybe disposable. The expandable or ratchet like devices may extend to thejoint without engaging or contacting the mold; alternatively, thesedevices may engage or contact the mold. Hinge-like mechanisms areapplicable. Similarly, jack-like mechanisms are useful. In principal,any mechanical or electrical device useful for fine-tuning the positionof the cut guide relative to the molds may be used. These embodimentsare helpful for soft-tissue tension optimization and ligament balancingin different joints for different static positions and during jointmotion.

A surgeon may desire to influence joint laxity as well as jointalignment. This can be optimized for different flexion and extension,abduction, or adduction, internal and external rotation angles. For thispurpose, for example, spacers or expandable or ratchet-like can beutilized that can be attached or that can be in contact with one or moremolds. The surgeon can intraoperatively evaluate the laxity or tightnessof a joint using spacers with different thickness or one or more spacerswith the same thickness or using such expandable or ratchet likedevices. For example, spacers or a ratchet like device can be applied ina knee joint in the presence of one or more molds and the flexion gapcan be evaluated with the knee joint in flexion. The knee joint can thenbe extended and the extension gap can be evaluated. Ultimately, thesurgeon will select an optimal combination of spacers or an optimalposition for an expandable or ratchet-like device for a given joint andmold. A surgical cut guide can be applied to the mold with the spacersor the expandable or ratchet-like device optionally interposed betweenthe mold and the cut guide or, in select embodiments, between the moldand the joint or the mold and an opposite articular surface. In thismanner, the exact position of the surgical cuts can be influenced andcan be adjusted to achieve an optimal result. Someone skilled in the artwill recognize other means for optimizing the position of the surgicalcuts or drill holes. For example, expandable or ratchet-like devices canbe utilized that can be inserted into the joint or that can be attachedor that can touch the mold. Hinge-like mechanisms are applicable.Similarly, jack-like mechanisms are useful. In principal, any mechanicalor electrical device useful for fine-tuning the position of the cutguide relative to the molds can be used.

The template and any related instrumentation such as spacers or ratchetscan be combined with a tensiometer to provide a better intraoperativeassessment of the joint. The tensiometer can be utilized to furtheroptimize the anatomic alignment and tightness of the joint and toimprove post-operative function and outcomes. Optionally, local contactpressures may be evaluated intraoperatively, for example using a sensorlike the ones manufactured by Tekscan, South Boston, Mass. The contactpressures can be measured between the mold and the joint or between themold and any attached devices such as a surgical cut block.

The template may be a mold that can be made of a plastic or polymer. Themold may be produced by rapid prototyping technology, in whichsuccessive layers of plastic are laid down, as know in the art. In otherembodiments, the template or portions of the template can be made ofmetal. The mold can be milled or made using laser based manufacturingtechniques.

The template may be casted using rapid prototyping and, for example,lost wax technique. It may also be milled. For example, a preformed moldwith a generic shape can be used at the outset, which can then be milledto the patient specific dimensions. The milling may only occur on onesurface of the mold, such as the surface that faces the articularsurface. Milling and rapid prototyping techniques may be combined.

Curable materials may be used which can be poured into forms that are,for example, generated using rapid prototyping. For example, liquidmetal may be used. Cured materials may optionally be milled or thesurface can be further refined using other techniques.

Metal inserts may be applied to plastic components. For example, aplastic mold may have at least one guide aperture to accept a reamingdevice or a saw. A metal insert may be used to provide a hard wall toaccept the reamer or saw. Using this or similar designs can be useful toavoid the accumulation of plastic or other debris in the joint when thesaw or other surgical instruments may get in contact with the mold.Other hard materials can be used to serve as inserts. These can alsoinclude, for example, hard plastics or ceramics.

In another embodiment, the mold does not have metallic inserts to accepta reaming device or saw. The metal inserts or guides may be part of anattached device that is typically in contact with the mold. A metallicdrill guide or a metallic saw guide may thus, for example, have metallicor hard extenders that reach through the mold thereby, for example, alsostabilizing any devices applied to the mold against the physical body ofthe mold.

The template may not only be used for assisting the surgical techniqueand guiding the placement and direction of surgical instruments. Inaddition, the templates can be utilized for guiding the placement of theimplant or implant components. For example, in the hip joint, tilting ofthe acetabular component is a frequent problem with total hiparthroplasty. A template can be applied to the acetabular wall with anopening in the center large enough to accommodate the acetabularcomponent that the surgeon intends to place. The template can havereceptacles or notches that match the shape of small extensions that canbe part of the implant or that can be applied to the implant. Forexample, the implant can have small members or extensions applied to thetwelve o'clock and six o'clock positions. By aligning these members withnotches or receptacles in the mold, the surgeon can ensure that theimplant is inserted without tilting or rotation. These notches orreceptacles can also be helpful to hold the implant in place while bonecement is hardening in cemented designs.

One or more templates can be used during the surgery. For example, inthe hip, a template can be initially applied to the proximal femur thatclosely approximates the 3D anatomy prior to the resection of thefemoral head. The template can include an opening to accommodate a saw.The opening is positioned to achieve an optimally placed surgical cutfor subsequent reaming and placement of the prosthesis. A secondtemplate can then be applied to the proximal femur after the surgicalcut has been made. The second template can be useful for guiding thedirection of a reamer prior to placement of the prosthesis. As can beseen in this, as well as in other examples, templates can be made forjoints prior to any surgical intervention. However, it is also possibleto make templates that are designed to fit to a bone or portions of ajoint after the surgeon has already performed selected surgicalprocedures, such as cutting, reaming, drilling, etc. The template canaccount for the shape of the bone or the joint resulting from theseprocedures.

In certain embodiments, the surgical assistance device comprises anarray of adjustable, closely spaced pins (e.g., plurality ofindividually moveable mechanical elements). One or more electronicimages or intraoperative measurements can be obtained providing objectcoordinates that define the articular and/or bone surface and shape.These objects' coordinates can be entered or transferred into thedevice, for example manually or electronically, and the information canbe used to create a surface and shape that will match all or portions ofthe articular and/or bone surface and shape by moving one or more of theelements, e.g. similar to an “image.” The device can include slots andholes to accommodate surgical instruments such as drills, curettes,k-wires, screws and saws. The position of these slots and holes may beadjusted by moving one or more of the mechanical elements. Typically, aposition will be chosen that will result in an anatomically desirablecut plane, reaming direction, or drill hole or instrument orientationfor subsequent placement of an articular repair system or forfacilitating the placement of an articular repair system.

Information about other joints or axis and alignment information of ajoint or extremity can be included when selecting the position of the,without limitation, cut planes, apertures, slots or holes on thetemplate. The biomechanical and/or anatomic axes may be derived usingabove-described imaging techniques including, without limitation, astandard radiograph, including a load bearing radiograph, for example anupright knee x-ray or a whole leg length film (e.g., hip to foot). Theseradiographs may be acquired in different projections, for exampleanteroposterior, posteroanterior, lateral, oblique etc. Thebiomechanical and anatomic axes may also be derived using other imagingmodalities such as CT scan or MRI scan, a CT scout scan or MRI localizedscans through portions or all of the extremity, either alone or incombination, as described in above embodiments. For example, when totalor partial knee arthroplasty is contemplated, a spiral CT scan may beobtained through the knee joint. The spiral CT scan through the kneejoint serves as the basis for generating the negative contourtemplate(s)/mold(s) that will be affixed to portions or all of the kneejoint. Additional CT or MRI scans may be obtained through the hip andankle joint. These may be used to define the centroids or centerpointsin each joint or other anatomic landmarks, for example, and then toderive the biomechanical and other axes.

In another embodiment, the biomechanical axis may be established usingnon-image based approaches including traditional surgical instrumentsand measurement tools such as intramedullary rods, alignment guides andalso surgical navigation. For example, in a knee joint, optical orradiofrequency markers can be attached to the extremity. The lower limbmay then be rotated around the hip joint and the position of the markerscan be recorded for different limb positions. The center of the rotationwill determine the center of the femoral head. Similar reference pointsmay be determined in the ankle joint etc. The position of the templatesor, more typically, the position of surgical instruments relative to thetemplates may then be optimized for a given biomechanical load pattern,for example in varus or valgus alignment. Thus, by performing thesemeasurements pre- or intraoperatively, the position of the surgicalinstruments may be optimized relative to the molds and the cuts can beplaced to correct underlying axis errors such as varus or valgusmalalignment or ante- or retroversion.

In various embodiments, upon imaging, a physical template of a joint,such as a knee joint, or hip joint, or ankle joint or shoulder joint canbe generated. The template can be used to perform image guided surgicalprocedures such as partial or complete joint replacement, articularresurfacing, or ligament repair. The template may include referencepoints or opening or apertures for surgical instruments such as drills,saws, burrs and the like.

In order to derive an optimal orientation of drill holes, cut planes,saw planes and the like, openings or receptacles in said template orattachments can be adjusted to account for at least one axis. The axiscan be anatomic or biomechanical, for example, for a knee joint, a hipjoint, an ankle joint, a shoulder joint or an elbow joint.

In one embodiment, only a single axis is used for placing and optimizingsuch drill holes, saw planes, cut planes, and or other surgicalinterventions. This axis may be, for example, an anatomical orbiomechanical axis. In one embodiment, a combination of axis and/orplanes can be used for optimizing the placement of the drill holes, sawplanes, cut planes or other surgical interventions. For example, twoaxes (e.g., one anatomical and one biomechanical) can be factored intothe position, shape or orientation of the 3D guided template and relatedattachments or linkages. For example, two axes, (e.g., one anatomicaland biomechanical) and one plane (e.g., the top plane defined by thetibial plateau), can be used. Alternatively, two or more planes can beused (e.g., a coronal and a sagittal plane), as defined by the image orby the patients anatomy.

Angle and distance measurements and surface topography measurements maybe performed in these one or more, two or more, or three or moremultiple planes, as contemplated and/or necessary. These anglemeasurements can, for example, yield information on varus or valgusdeformity, flexion or extension deficit, hyper or hypo-flexion or hyper-or hypo-extension, abduction, adduction, internal or external rotationdeficit, or hyper- or hypo-abduction, hyper- or hypo-adduction, hyper-or hypo-internal or external rotation.

Single or multi-axis line or plane measurements can then be utilized todetermine various angles of correction, e.g., by adjusting surgical cutor saw planes or other surgical interventions. Typically, two axiscorrections will be desirable over a single axis correction, a two planecorrection will be desirable over a single plane correction, and soforth.

In accordance with another embodiment, more than one drilling, cut,boring and/or reaming or other surgical intervention is performed for aparticular treatment such as the placement of a joint resurfacing orreplacing implant, or components thereof. These two or more surgicalinterventions (e.g., drilling, cutting, reaming, sawing) are made inrelationship to a biomechanical axis, and/or an anatomical axis and/oran implant axis. The 3D guidance template or attachments or linkagesthereto include two or more openings, guides, apertures or referenceplanes to make at least two or more drillings, reamings, borings,sawings or cuts in relationship to a biomechanical axis, an anatomicalaxis, an implant axis or other axis derived therefrom or relatedthereto.

While in simple embodiments it is possible that only a single cut ordrilling will be made in relationship to a biomechanical axis, ananatomical axis, an implant axis and/or an axis related thereto, in mostmeaningful implementations, two or more drillings, borings, reamings,cutting and/or sawings will be performed or combinations thereof inrelationship to a biomechanical, anatomical and/or implant axis.

For example, an initial cut may be placed in relationship to abiomechanical axis of particular joint. A subsequent drilling, cut orother intervention can be performed in relation to an anatomical axis.Both can be designed to achieve a correction in a biomechanical axisand/or anatomical axis. In another example, an initial cut can beperformed in relationship to a biomechanical axis, while a subsequentcut is performed in relationship to an implant axis or an implant plane.Any combination in surgical interventions and in relating them to anycombination of biomechanical, anatomical, implant axis or planes relatedthereto is possible. In various embodiments, it is desirable that asingle cut or drilling be made in relationship to a biomechanical oranatomical axis. Subsequent cuts or drillings or other surgicalinterventions can then be made in reference to said first intervention.These subsequent interventions can be performed directly off the same 3Dguidance template or they can be performed by attaching surgicalinstruments or linkages or reference frames or secondary or othertemplates to the first template or the cut plane or hole and the likecreated with the first template.

FIG. 12 shows an example of a surgical tool 410 having one surface 400matching the geometry of an articular surface of the joint. Also shownis an aperture 415 in the tool 410 capable of controlling drill depthand width of the hole and allowing implantation or insertion of implant420 having a press-fit design.

In another embodiment, a frame can be applied to the bone or thecartilage in areas other than the diseased bone or cartilage. The framecan include holders and guides for surgical instruments. The frame canbe attached to one or more previously defined anatomic reference points.Alternatively, the position of the frame can be cross-registeredrelative to one, or more, anatomic landmarks, using an imaging test orintraoperative measurement, for example one or more fluoroscopic imagesacquired intraoperatively. One or more electronic images orintraoperative measurements including using mechanical devices can beobtained providing object coordinates that define the articular and/orbone surface and shape. These objects' coordinates can be entered ortransferred into the device, for example manually or electronically, andthe information can be used to move one or more of the holders or guidesfor surgical instruments. Typically, a position will be chosen that willresult in a surgically or anatomically desirable cut plane or drill holeorientation for subsequent placement of an articular repair system.Information about other joints or axis and alignment information of ajoint or extremity can be included when selecting the position of theseslots or holes.

In various embodiments, the template may include a reference element,such as a pin, that upon positioning of the template on the articularsurface, establishes a reference plane relative to a biomechanical axisor an anatomical axis or plane of a limb. For example, in a knee surgerythe reference element may establish a reference plane from the center ofthe hip to the center of the ankle. In other embodiments, the referenceelement may establish an axis that subsequently be used a surgical toolto correct an axis deformity.

In these embodiments, the template can be created directly from thejoint during surgery or, alternatively, created from an image of thejoint, for example, using one or more computer programs to determineobject coordinates defining the surface contour of the joint andtransferring (e.g., dialing-in) these co-ordinates to the tool.Subsequently, the tool can be aligned accurately over the joint and,accordingly, the surgical instrument guide or the implant will be moreaccurately placed in or over the articular surface.

In both single-use and re-useable embodiments, the tool can be designedso that the instrument controls the depth and/or direction of the drill,i.e., the drill cannot go any deeper into the tissue than the instrumentallows, and the size of the hole or aperture in the instrument can bedesigned to essentially match the size of the implant. The tool can beused for general prosthesis implantation, including, but not limited to,the articular repair implants described herein and for reaming themarrow in the case of a total arthroplasty.

Identification and preparation of the implant site and insertion of theimplant can be supported by a surgical navigation system. In such asystem, the position or orientation of a surgical instrument withrespect to the patient's anatomy can be tracked in real-time in one ormore 2D or 3D images. These 2D or 3D images can be calculated fromimages that were acquired preoperatively, such as MR or CT images.Non-image based surgical navigation systems that find axes or anatomicalstructures, for example with use of joint motion, can also be used. Theposition and orientation of the surgical instrument as well as the moldincluding alignment guides, surgical instrument guides, reaming guides,drill guides, saw guides, etc. can be determined from markers attachedto these devices. These markers can be located by a detector using, forexample, optical, acoustical or electromagnetic signals.

Identification and preparation of the implant site and insertion of theimplant can also be supported with use of a C-arm system. The C-armsystem can afford imaging of the joint in one or multiple planes. Themultiplanar imaging capability can aid in defining the shape of anarticular surface. This information can be used to selected an implantwith a good fit to the articular surface. Currently available C-armsystems also afford cross-sectional imaging capability, for example foridentification and preparation of the implant site and insertion of theimplant. C-arm imaging can be combined with administration ofradiographic contrast.

In various embodiments, the surgical devices described herein caninclude one or more materials that harden to form a mold of thearticular surface. In various embodiments, the materials used arebiocompatible, such as, without limitation, acylonitrile butadienestyrene, polyphenylsulfone and polycarbonate. As used herein“biocompatible” shall mean any material that is not toxic to the body(e.g., produces a negative reaction under ISO 10993 standards,incorporated herein by reference). In various embodiments, thesebiocompatible materials may be compatible with rapid prototypingtechniques.

In further embodiments, the mold material is capable of heatsterilization without deformation. An exemplary mold material ispolyphenylsulfone, which does not deform up to a temperature of 207° C.Alternatively, the mold may be capable of sterilization using gases,e.g. ethyleneoxide. The mold may be capable of sterilization usingradiation, e.g. γ-radiation. The mold may be capable of sterilizationusing hydrogen peroxide or other chemical means. The mold may be capableof sterilization using any one or more methods of sterilization known inthe art or developed in the future.

A wide-variety of materials capable of hardening in situ includepolymers that can be triggered to undergo a phase change, for examplepolymers that are liquid or semi-liquid and harden to solids or gelsupon exposure to air, application of ultraviolet light, visible light,exposure to blood, water or other ionic changes. (See, also, U.S. Pat.No. 6,443,988 to Felt et al. issued Sep. 3, 2002 and documents citedtherein). Non-limiting examples of suitable curable and hardeningmaterials include polyurethane materials (e.g., U.S. Pat. No. 6,443,988to Felt et al., U.S. Pat. No. 5,288,797 to Khalil issued Feb. 22, 1994,U.S. Pat. No. 4,098,626 to Graham et al. issued Jul. 4, 1978 and U.S.Pat. No. 4,594,380 to Chapin et al. issued Jun. 10, 1986; and Lu et al.(2000) BioMaterials 21(15):1595-1605 describing porous poly(L-lactideacid foams); hydrophilic polymers as disclosed, for example, in U.S.Pat. No. 5,162,430; hydrogel materials such as those described in Wakeet al. (1995) Cell Transplantation 4(3):275-279, Wiese et al. (2001) J.Biomedical Materials Research 54(2):179-188 and Marler et al. (2000)Plastic Reconstruct. Surgery 105(6):2049-2058; hyaluronic acid materials(e.g., Duranti et al. (1998) Dermatologic Surgery 24(12):1317-1325);expanding beads such as chitin beads (e.g., Yusof et al. (2001) J.Biomedical Materials Research 54(1):59-68); crystal free metals such asLiquidmetals®, and/or materials used in dental applications (See, e.g.,Brauer and Antonucci, “Dental Applications” pp. 257-258 in “ConciseEncyclopedia of Polymer Science and Engineering” and U.S. Pat. No.4,368,040 to Weissman issued Jan. 11, 1983). Any biocompatible materialthat is sufficiently flowable to permit it to be delivered to the jointand there undergo complete cure in situ under physiologically acceptableconditions can be used. The material can also be biodegradable.

The curable materials can be used in conjunction with a surgical tool asdescribed herein. For example, the surgical tool can be a template thatincludes one or more apertures therein adapted to receive injections andthe curable materials can be injected through the apertures. Prior tosolidifying in situ the materials will conform to the articular surface(subchondral bone and/or articular cartilage) facing the surgical tooland, accordingly, will form a mirror and/or negative image impression ofthe surface upon hardening, thereby recreating a normal or near normalarticular surface.

In addition, curable materials or surgical tools can also be used inconjunction with any of the imaging tests and analysis described herein,for example by molding these materials or surgical tools based on animage of a joint. For example, rapid prototyping may be used to performautomated construction of the template. The rapid prototyping mayinclude the use of, without limitation, 3D printers, stereolithographymachines or selective laser sintering systems. Rapid prototyping is atypically based on computer-aided manufacturing (CAM). Although rapidprototyping traditionally has been used to produce prototypes, they arenow increasingly being employed to produce tools or even to manufactureproduction quality parts. In an exemplary rapid prototyping method, amachine reads in data from a CAD drawing, and lays down successivemillimeter-thick layers of plastic or other engineering material, and inthis way the template can be built from a long series of cross sections.These layers are glued together or fused (often using a laser) to createthe cross section described in the CAD drawing.

FIG. 13 is a flow chart illustrating the steps involved in designing amold for use in preparing a joint surface. Optionally, the first stepcan be to measure the size of the area of the diseased cartilage orcartilage loss 2100, Once the size of the cartilage loss has beenmeasured, the user can measure the thickness of the adjacent cartilage2120, prior to measuring the curvature of the articular surface and/orthe subchondral bone 2130. Alternatively, the user can skip the step ofmeasuring the thickness of the adjacent cartilage 2102. Once anunderstanding and determination of the shape of the subchondral bone isdetermined, either a mold can be selected from a library of molds 3132or a patient specific mold can be generated 2134. In either event, theimplantation site is then prepared 2140 and implantation is performed2142. Any of these steps can be repeated by the optional repeat steps2101, 2121, 2131, 2133, 2135, 2141.

A variety of techniques can be used to derive the shape of the template,as described above. For example, a few selected CT slices through thehip joint, along with a full spiral CT through the knee joint and a fewselected slices through the ankle joint can be used to help define theaxes if surgery is contemplated of the knee joint. Once the axes aredefined, the shape of the subchondral bone can be derived, followed byapplying standardized cartilage loss.

Methodologies for stabilizing the 3D guidance templates will now bedescribed. The 3D guide template may be stabilized using multiplesurgical tools such as, without limitation: K-wires; a drill bitanchored into the bone and left within the template to stabilize itagainst the bone; one or more convexities or cavities on the surfacefacing the cartilage; bone stabilization against intra/extra articularsurfaces, optionally with extenders, for example, from an articularsurface onto an extra-articular surface; and/or stabilization againstnewly placed cuts or other surgical interventions.

Specific anatomic landmarks may be selected in the design and make ofthe 3D guide template in order to further optimize the anatomicstabilization. For example, a 3D guidance template may be designed towith an anatomical relief or other such structure (or absence ofstructure) to cover portions or all off an osteophyte or bone spur inorder to enhance anchoring of the 3D guide template against theunderlying articular anatomy. The 3D guidance template may be designedto the shape of a trochlear or intercondylar notch and can encompassmultiple anatomic areas such as a trochlea, a medial and a lateralfemoral condyle at the same time. In the tibia, a 3D guide template maybe designed to encompass a medial and lateral tibial plateau at the sametime and it can optionally include the tibial spine for optimizedstabilization and cross-referencing. In a hip, the fovea capitis may beutilized in order to stabilize a 3D guide template. Optionally, thesurgeon may elect to resect the ligamentum capitis femoris in order toimprove the stabilization. Also in the hip, an acetabular mold can bedesigned to extend into the region of the tri-radiate cartilage, themedial, lateral, superior, inferior, anterior and posterior acetabularwall or ring. By having these extensions and additional features forstabilization, a more reproducible position of the 3D template can beachieved with resulted improvement in accuracy of the surgicalprocedure. Typically, a template with more than one convexity orconcavity or multiple convexities or concavities (including relevantanatomical relief surfaces) will provide better cross-referencing in theanatomic surface and higher accuracy and higher stabilization thancompared to a mold that has only few surface features such as a singularconvexity. Thus, in order to improve the implementation andintraoperative accuracy, careful surgical planning and preoperativeplanning is desired, that encompasses more than one convexity, more thantwo convexities and/or more than three convexities, or that encompassesmore than one concavity, more than two concavities or more than threeconcavities on an articular surface or adjoined surface, including boneand cartilage outside the weight-bearing surface.

In another embodiment, more than one convexity and concavity, more thantwo convexities and concavities and/or more then three convexities andconcavities are included in the surface of the mold in order to optimizethe interoperative cross-referencing and in order to stabilize the moldprior to any surgical intervention.

Turning now to particular 3D surgical template configurations and totemplates for specific joint applications which are intended to teachthe concept of the design as it would then apply to other joints in thebody.

i. 3D Guidance Template Configurations/Positioning

In various embodiments, the 3D guidance template may include a surfacethat duplicates the inner surface of an implant or an implant component,and/or that conforms to an articular surface, at least partially. Morethan one of the surfaces of the template may match or conform to one ormore of the surfaces or portions of one or more of these surfaces of animplant, implant component, and/or articular surface.

FIG. 20 shows an example of a 3D guidance template 3000 in a hip joint,in accordance with one embodiment, wherein the template has extenders3010 extending beyond the margin of the joint to provide for additionalstability and to fix the template in place. The surface of the templatefacing the joint 3020 is a mirror and/or negative image of a portion ofthe joint that is not affected by the arthritic process 3030. Bydesigning the template to be a mirror and/or negative image of at leasta portion of the joint that is not affected by the arthritic process,greater reproducibility in placing the template can be achieved. In thisdesign, the template spares the arthritic portions 3040 of the joint anddoes not include them in its joint facing surface. The template canoptionally have metal sleeves 3050 to accommodate a reamer or othersurgical instruments, to protect a plastic. The metal sleeves or,optionally, the template can also include stops 3060 to limit theadvancement of a surgical instrument once a predefined depth has beenreached.

FIG. 21 shows another embodiment of a 3D guidance template 3100 for anacetabulum. The articular surface is roughened 3110 in some sections bythe arthritic process. At least a portion of the template 3120 is madeto be a mirror and/or negative image of the articular surface altered bythe arthritic process 3110. By matching the template to the joint inareas where it is altered by the arthritic process improvedintraoperative localization and improved fixation can be achieved. Inother section, the template can be matched to portions of the joint thatare not altered by the arthritic process 3130.

FIG. 22 shows another embodiment of a 3D guidance template 3200 designedto guide a posterior cut 3210 using a posterior reference plane 3220.The joint facing surface of the template 3230 is, at least in part, amirror and/or negative image of portions of the joint that are notaltered by the arthritic process. The arthritic process includes anosteophyte 3240. The template includes a recess or anatomical relief3250 that helps avoid the osteophyte 3240. The template is at least inpart substantially matched to portions of the joint that are notinvolved by the arthritic process.

FIG. 23 shows another embodiment of a 3D guidance template 3300 designedto guide an anterior cut 3310 using an anterior reference plane 3320.The joint facing surface of the template 3230 is, at least in part, amirror and/or negative image of portions of the joint that are alteredby the arthritic process. The arthritic process includes an osteophyte3240. The joint facing surface of the template 3230 is a mirror and/ornegative image of the arthritic process, at least in part, including analternative embodiment of an anatomical relief surface to accommodatethe osteophyte 3240. The template in this embodiment is at least in partmatched to portions of the joint that are involved by the arthriticprocess as well as the adjacent uninvolved joint surface structure.

FIG. 24 shows another embodiment of a 3D guidance template 3400 forguiding a tibial cut (not shown), wherein the tibia 3410 includes anarthritic portion 3420, in this example a subchondral cyst 3430. Thetemplate is designed to avoid contacting the entirety of the arthriticprocess by including an anatomic relief surface 3440 spanning across thedefect or cyst. If desired, the surface 3440 could include anotherembodiment of an anatomical relief that desirably avoids substantiallycontact with and/or more closely follows and/or fills the positiveand/or negative surface features of the tibia.

FIG. 25 shows another embodiment of a 3D guidance template 3500 forguiding a tibial cut (not shown), wherein the tibia 3510 includes anarthritic portion 3520, in this example a subchondral cyst 3530. Thetemplate is designed to include the arthritic process 3520 by extendingone embodiment of an anatomic relief surface 3540 into the defect orcyst 3530. The surface of the template facing the joint 3550 is a mirrorand/or negative image of portions of normal joint 3560 and portions ofthe joint that are altered by the arthritic process 3530. The interfacebetween normal and arthritic tissue is included in the shape of thetemplate 3520.

FIGS. 26 A-D show a knee joint with a femoral condyle 3600 including anormal 3610 and arthritic 3620 region, in accordance with variousembodiments. The interface 3630 between normal 3610 and arthritic 3620tissue is shown. The template is designed to guide a posterior cut 3640using a guide plane 3650 or guide aperture 3660.

In one embodiment shown in FIG. 26 A the surface of the template facingthe joint 3670 is a mirror and/or negative image of at least portions ofthe surface of the joint that is healthy or substantially unaffected bythe arthritic process. A recessed area or anatomical relief 3670 can bepresent to avoid contact with the diseased joint region. This design canbe favorable when an imaging test is used that does not providesufficient detail about the diseased region of the joint to accuratelygenerate a template.

In a similar embodiment shown in FIG. 26 B the surface of the templatefacing the joint 3670 is a mirror and/or negative image of at leastportions of the surface of the joint that is healthy or substantiallyunaffected by the arthritic process. The diseased area 3620 is coveredby the template, but the template includes an anatomical relief portionthat is not substantially in contact with the diseased area.

In another embodiment shown in FIG. 26C the surface of the templatefacing the joint 3670 is a mirror and/or negative image of at leastportions of the surface of the joint that are arthritic. The diseasedarea 3620 is covered by the template, and the template is in closecontact with it. This design can be advantageous to obtain greateraccuracy in positioning the template if the arthritic area is welldefined on the imaging test, e.g. with high resolution spiral CT or nearisotropic MRI acquisitions or MRI with image fusion. This design canalso provide enhanced stability during surgical interventions by morefirmly fixing the template against the irregular underlying surface.

In another embodiment shown in FIG. 26 D the surface of the templatefacing the joint 3670 is a mirror and/or negative image of at leastportions of the surface of the joint that are arthritic. The diseasedarea 3620 is covered by the template, and the template is in closecontact with it. Moreover, healthy or substantially normal regions 3610are covered by the template and the template is in close contact withthem. The template is also closely mirroring the shape of the interfacebetween substantially normal or near normal and diseased joint tissue3630. This design can be advantageous to obtain even greater accuracy inpositioning the template due to the change in surface profile or contourat the interface and resultant improved placement of the template on thejoint surface. This design can also provide enhanced stability duringsurgical interventions by more firmly fixing and anchoring the templateagainst the underlying surface and the interface 3630.

In various embodiments, the template may include guide apertures orreference points for two or more planes, or at least one of a cut planeand one of a drill hole or reaming opening for a peg or implant stem.

The distance between two opposing, articulating implant components maybe optimized intraoperatively for different pose angles of the joint orjoint positions, such as different degrees of section, extension,abduction, adduction, internal and external rotation. For example,spacers, typically at least partially conforming to the template, may beplaced between the template of the opposite surface, where the oppositesurface can be the native, uncut joint, the cut joint, the surgicallyprepared joint, the trial implant, or the definitive implant componentfor that articular surface. Alternatively, spacers may be placed betweenthe template and the articular surface for which it will enablesubsequent surgical interventions. For example, by placing spacersbetween a tibial template and the tibia, the tibial cut height can beoptimized. The thicker the spacer, or the more spacers interposedbetween the tibial template and the tibial plateau the less deep the cutwill be, i.e. the less bone will be removed from the top of the tibia.

The spacers may be non-conforming to the template, e.g. they may be of aflat nature. The spacers may be convex or concave or include multipleconvexities or concavities. The spacers may be partially conforming tothe template. For example, in one embodiment, the surface of the spaceroptionally facing the articular surface can be molded and individualizedto the articular surface, thereby forming a template/mold, while theopposite surface of the spacer can be flat or curved or have any othernon-patient specific design. The opposite surface may allow forplacement of blocks or other surgical instruments or for linkages toother surgical instruments and measurement devices.

In another embodiment, the template may include multiple slots spaced atequal distance or at variable distances wherein these slots allow toperform cuts at multiple cut heights or cut depths that can be decidedon intraoperatively. In another embodiment, the template may include aratchet-like mechanism wherein the ratchet can be placed between thearticular surface and the template or between the template and theopposite surface wherein the opposite surface may include the native,uncut opposite surface, the cut opposite surface, an opposite surfacetemplate, a trial implant or the implant component designed for theopposite surface. By using a ratchet-like device, soft tissue tensioncan be optimized, for example, for different pose angles of the joint orjoint positions such as flexion, extension, abduction, adduction,internal rotation and external rotation at one or more degrees for eachdirection.

Optimizing soft tissue tension will improve joint function thatadvantageously enhances postoperative performance. Soft tissue tensionmay, for example, be optimized with regard to ligament tension or muscletension but also capsular tension. In the knee joint, soft tissuetension optimization includes typically ligament balancing, e.g. thecruciate ligaments and/or the collateral ligaments, for differentdegrees of knee flexion and knee extension.

In one disclosed embodiment, a 3D guidance template may attach to two ormore points on the joint. In other embodiments, a template may attach tothree or more points on the joint, four or more points on the joint,five or more points on the joint, six or more points on the joint, sevenor more points on the joint, ten or more points on the joint, or moreportions for the entire surface to be replaced.

In another embodiment, the template may include one or more linkages forsurgical instruments. The linkages may also be utilized for attachingother measurement devices such as alignment guides, intramedullaryguides, laser pointing devices, laser measurement devices, opticalmeasurement devices, radio frequency measurement devices, surgicalnavigation and the like. Someone skilled in the art will recognize manysurgical instruments and measurement in alignment devices may beattached to the template. Alternatively, these surgical instruments oralignment devices may be included within the template.

In another embodiment, a link or a linkage may be attached or may beincorporated or may be part of a template that rests on a firstarticular surface. Said link or linkage may further extend to a secondarticular surface which is typically an opposing articular surface. Saidlink or linkage can thus help cross-reference the first articularsurface with the second articular surface, ultimately assisting theperformance of surgical interventions on the second articular surfaceusing the cross reference to the first articular surface. The secondarticular surface may optionally be cut with a second template.Alternatively, the second articular surface may be cut using a standardsurgical instrument, non-individualized, that is cross referenced viathe link to the surgical mold placed on the first articular surface. Thelink or linkage may include adjustment means, such as ratchets,telescoping devices and the like to optimize the spatial relationshipbetween the first articular surface and the second, opposing articularsurface. This optimization may be performed for different degrees ofjoint flexion, extension, abduction, adduction and rotation.

In another embodiment, the linkage may be made to the cut articularsurface or, more general, an articular surface that has been alteredusing a template and related surgical intervention. Thus, crossreference can be made from the first articular surface from a moldattached to said first articular surface, the mold attached to asurgically altered, for example, cut articular surface, the surgicalinstrument attached to said articular surface altered using the mold,e.g. cut or drilled, and the like. Someone skilled in the art willeasily recognize multiple different variations of this approach.Irrespective of the various variations, in a first step the articularsurface is surgically altered, for example, via cutting, drilling orreaming using a mold while in the second step cross reference isestablished with a second articular surface.

By establishing cross reference between said first and said secondarticular surface either via the template and/or prior to or after asurgical intervention, the surgical intervention performed on the secondarticular surface can be performed using greater accuracy and improvedusability in relation to said articulating, opposing first articularsurface.

FIGS. 27A-D show multiple templates with linkages on the same articularsurface (A-C) and to an opposing articular surface (D), in accordancewith various embodiments. The biomechanical axis is denoted as 3700. Ahorizontal femoral cut 3701, an anterior femoral cut 3702, a posteriorfemoral cut 3703, an anterior chamfer cut 3704 and a posterior chamfercut 3705 are planned in this example. A first template 3705 is appliedin order to determine the horizontal cut plane and to perform the cut.The cut is perpendicular to the biomechanical axis 3700. The firsttemplate 3705 has linkages or extenders 3710 for connecting a secondtemplate 3715 for the anterior cut 3702 and for connecting a thirdtemplate 3720 for the posterior cut 3703. The linkages 3710 connectingthe first template 3705 with the second 3715 and third template 3720help in achieving a reproducible position of the templates relative toeach other. At least one of the templates, such as the first template3705, will have a surface 3706 that is a mirror and/or negative image ofthe articular surface 3708. In this example, all three templates havesurface facing the joint that is a mirror and/or negative image of thejoint, although one template having a surface conforming to the jointsuffices in many applications and embodiments.

A fourth template 3725 may optionally be used in order to perform ananterior chamfer cut 3704. The fourth template may have a guide apertureor reference plane 3730 that can determine the anterior chamfer cut3704. The fourth template can, but need not always have, at least onesurface 3735 matching one or more cut articular surfaces 3740. Thefourth template may have one or more outriggers or extenders 3745stabilizing the template against the cut or uncut articular surface.

A fifth template 3750 may optionally be used to perform a anteriorchamfer cut 3705. The fifth template may have a guide aperture orreference plane 3755 that can determine the posterior chamfer cut 3705.The fifth template may have at least one surface 3735 matching one ormore cut articular surfaces 3740. Oblique planes 3760 may help tofurther stabilize the template during the procedure. The fifth templatemay have one or more outriggers or extenders 3745 stabilizing thetemplate against the cut or uncut articular surface.

In another embodiment, an opposite articular side 3765 may be cut inreference to a first articular side 3766. Any order or sequence ofcutting is possible: femur first then tibia, tibia first then femur,patella first, and so forth. A template 3770 may be shaped to the uncutor, in this example, cut first articular side. The template may havestabilizers against the first articular surface, for example withextenders 3772 into a previously created peg hole 3773 for an implant.The template may have a linkage or an extender 3775 to a secondarticular surface 3765. Surgical instruments may be attached to thelinkage or extender 3775. In this example, a tibial cut guide 3778 withmultiple apertures or reference planes 3779 for a horizontal tibial cutis attached. The tibial cut guide may but may not have a surfacematching the tibial surface.

By referencing a first, e.g. femoral, to a second, e.g. tibial cutgreater accuracy can be achieved in the alignment of these cuts, whichwill result in improved implant component alignment and less wear.Ratchet like devices 3785 or hinge like devices or spacers may beinserted into the space between the first and the second articularsurface and soft-tissue tension and ligament balancing can be evaluatedfor different distances achieved between the first 3766 and second 3765articular surface, with one or more of them being cut or uncut. In thismanner, soft-tissue tension and ligament balancing can be tested duringdifferent pose angles, e.g. degrees of flexion or extension. Optionally,tensiometers can be used. Once an ideal soft-tissue tension and/orligament balancing has been achieved, the tibial cut may be performedthrough one of the guide apertures 3779 in reference to the femoral cut.

FIG. 28 is an example demonstrating a deviation in the AP plane of thefemoral 3801 and tibial 3803 axes in a patient. Axis deviations can bedetermined in any desired plane including the AP plane, not only the MLplane. The axis deviation can be measured. The desired correction can bedetermined and the position, orientation and shape of a 3D guidancetemplate can be adjusted in order to achieve the necessary correction.The correction may, for example, be designed to achieve a result whereinthe femoral 3801 and tibial 3803 axes will coincide with thebiomechanical axis 3805.

The various embodiments described herein optionally provide for trialimplants and trial devices that help test intraoperatively the result ofthe surgical intervention achieved using the 3D guidance mold. Trialimplants or devices can be particularly useful for subsequentadjustments and fine-tuning of the surgical intervention, for example,optimizing soft tissue tension in different articular pose angles.

In another embodiment, the templates may also allow for intraoperativeadjustments. For example, the template may include an opening for a pin.The pin can be placed in the bone and the template can be rotated aroundthe pin thereby optimizing, for example, medial and lateral ligamenttension in a knee joint or thereby optimizing the cut orientation andresultant rotation and alignment of an implant relative to the anatomicor biomechanical axis.

In another embodiment, standard tools including alignment guides may beattached to the mold, via linkages for example, and the attachment canallow for additional adjustments in mold and subsequently implantalignment and rotation.

The above-described embodiments can be particularly useful foroptimization of soft tissue tension including ligament balancing, forexample, in a knee joint. Optimization of soft tissue tension canadvantageously improve post-operative function and range of motion.

Linkages may also be utilized to stabilize and fix additional molds orsurgical instruments on the articular surface.

Moreover, linkages can allow separation of one large mold into multiplesmaller molds. The use of multiple smaller, linked molds advantageouslyenable smaller surgical axis with the potential to enhance musclesparing and to reduce the size of the skin cut.

In another embodiment, all or portions of the template may be made ofmetal, metal-alloys, teflon, ceramics. In various other embodiments,metal, metal-alloys, teflon, ceramics and other hard materials,typically materials that offer a hardness of, without limitation,greater than shore 60D, is placed in areas where the surgicalinstruments will be in contact with the template.

ii. 3D Guidance Molds for Ligament Repair and Replacement

In various embodiments, 3D guidance molds may also be utilized forplanning the approach and preparing the surgical intervention andconducting the surgical intervention for ligament repair andreplacement.

In one example, the anterior cruciate ligament is replaced using a 3Dguidance mold. The anterior cruciate ligament is a collagenous structurelocated in the center of the knee joint, and is covered by the synovialsheath. The ligament has an average length of thirty (30) tothirty-eight (38) millimeters and an average width of ten (10) to eleven(11) millimeters. The ligament is proximally attached to the posterioraspect of the lateral femoral condyle's medial surface. The ligamentpasses anteriorly, medially and distally within the joint to itsattachment at the anteromedial region of the tibial plateau, between thetibial eminences. The distal portion of the ligament fans out to createa large tibial attachment known as the footprint of the ligament. Theligament has two functional subdivisions which include the anteromedialband and the posterolateral band. The posterolateral band is taut whenthe knee is extended and the anteromedial band becomes taut when theknee is flexed. Because of its internal architecture and attachmentssides on femur and tibia, the ACL provides restraint to anteriortranslation and internal rotation of the tibia in angulation andhyperextension of the knee. The prevalence of ACL injuries are about 1in 3,000 subjects in the United States and approximately 250,000 newinjuries each year.

Other tendon and ligament injuries, for example, including the rotatorcuff, the ankle tendons and ligaments, or the posterior cruciateligament can also be highly prevalent and frequent.

Selecting the ideal osseous tunnel sights is a crucial step in ligamentreconstruction, for example, the anterior and posterior cruciateligament.

In the following paragraphs, embodiments will be described in detail asthey can be applied to the anterior cruciate ligament. However, thevarious embodiments mentioned below and modifications thereof may oftenbe applicable to other ligaments, including the posterior cruciateligament and also tendons such as tendons around the ankle joint orrotator cuff and shoulder joint.

Anterior Cruciate Ligament

The normal anterior cruciate ligament is composed of a large number offibers. Each fiber can have a different length, a different origin and adifferent insertion and is frequently under different tension during therange of motion of the knee joint. One of the limitations of today's ACLgraft is that they have parallel fibers. Thus, even with ideal selectionof the placement of the osseous tunnels, fibers of an ACL graft willundergo length and tension changes with range of motion. Therefore,today's ACL replacement cannot duplicate the original ligament. However,placing the center of the osseous tunnels at the most isometric points,maximizes the stability that can be obtained during motion and minimizeslater on graft wear and ultimately resultant failure.

In illustrative embodiments, 3D guidance templates may be selected anddesigned to enable highly accurate, reproducible and minimally invasivegraft tunnels in the femur and the tibia.

In one embodiment, imaging such as MRI is performed pre-operatively. Theimages can be utilized to identify the origin of the ligament and itsinsertion onto the opposing articular surface, in the case of ananterior cruciate ligament, the tibia. Once the estimated location ofthe origin and the footprint, i.e. the insertion of the ligament hasbeen identified, 3D guidance templates may be made to be applied tothese areas or their vicinity.

The 3D guidance templates may be made and shaped to the articularsurface, for example, adjacent to the intended tunnel location or theymay be shaped to bone or cartilage outside the weight bearing zone, forexample, in the intercondylar notch. A 3D guidance template for femoralor tibial tunnel placement for ACL repair may include blocks,attachments or linkages for reference points or guide aperture to guideand direct the direction and orientation of a drill, and optionally,also the drill depth. Optionally, the 3D guidance templates may behollow. The 3D guidance templates may be circular, semi-circular orellipsoid. The 3D guidance templates may have a central opening toaccommodate a drill.

In one embodiment, the 3D guidance template is placed on, over or nearthe intended femoral or tibial entry point and subsequently the drillhole. Once proper anatomic positioning has been achieved, the ligamenttunnel can be created. The 3D guidance template, its shape, position,and orientation, may be optimized to reflect the desired tunnel locationin the femur and the tibia, wherein the tunnel location, position,orientation and angulation is selected to achieve the best possiblefunctional results. Additional considerations in placing the femoral ortibial tunnel includes a sufficient distance to the cortical bone inorder to avoid failure or fracture of the tunnel.

Thus, optionally, the distance of the tunnel to the adjacent corticalbone and also other articular structures may optionally be factored intothe position, shape and orientation of the femoral or tibial 3D guidancetemplates in order to achieve the optimal compromise between optimalligament function and possible post-operative complications such asfailure of the tunnel.

In another embodiment, the imaging test may be utilized to determine theorigin and insertion of the ligament. This determination can beperformed on the basis of bony landmarks identified on the scan, e.g. aCT scan or MRI scan. Alternatively, this determination can be performedby identifying ligament remnants, for example, in the area of theligament origin and ligament attachment. By determining the origin andthe insertion of the ligament the intended graft length may be estimatedand measured. This measurement may be performed for different poseangles of the joint such as different degrees of flexion, extension,abduction, adduction, internal and external rotation.

In another embodiment, the imaging test may be utilized to identify theideal graft harvest site wherein the graft harvest site can optionallybe chosen to include sufficiently long ligament portion and underlyingbone block proximally and distally in order to fulfill the requirementfor graft length as measured earlier in the imaging test. An additional3D guidance template for the same 3D guidance templates, possibly withlinkages, may be utilized to harvest the ligament and bone from thedonor site in the case of an autograft. Optionally, 3D guidancetemplates may also be utilized or designed or shaped or selected toguide the extent of an optional notchplasty. This can include, forexample, the removal of osteophytes.

In the case of an ACL replacement, the 3D guidance templates may in thismanner optimize selection of femoral and tibial tunnel sites. Tunnelsites may even be optimized for different knee pose angles, i.e. jointpositions, and different range of motion. Selecting the properlypositioned femoral tunnel site ensures maximum post operative kneestability.

The intra-articular site of the tibial tunnel has less effect on changesin graft length but its position can be optimized using properplacement, position, and shape of 3D guidance templates to preventintercondular notch impingement.

Moreover, the 3D guidance templates may include an optional stop for thedrill, for example, to avoid damage to adjacent neurovascular bundles oradjacent articular structures, including the articular cartilage orother ligaments.

Optionally, the 3D guidance templates may also include a stop, forexample, for a drill in order to include the drill depth.

The direction and orientation of the tibial tunnel and also the femoraltunnel may be determined with use of the 3D guidance template, wherebyit will also include selection of an optimal tunnel orientation in orderto match graft length as measured pre-operatively with the tunnel lengthand the intra-articular length of the graft ligament.

In one embodiment, a tibial 3D guidance template is, for example,selected so that its opening is located immediately posterior to theanatomic center of the ACL tibial footprint. Anatomic landmarks may befactored into the design, shape, orientation, and position of the tibialguidance template, optionally. These include, without limitation, theanterior horn of the lateral meniscus, the medial tibial spine, theposterior cruciate ligament, and the anterior cruciate ligament stump.

The tunnel site may be located utilizing the 3D guidance template in theanterior posterior plane by extending a line in continuation with theinner edge of the anterior horn of the lateral meniscus. This plane willtypically be located six (6) to seven (7) millimeters anterior to theinterior border of the PCL. The position, shape and orientation of the3D guidance template will be typically so that the resultant tibialtunnel and the resultant location and orientation of the ACL graft, oncein place, may touch the lateral aspect of the PCL, but will notsignificantly deflect it. Similarly, the location of the tibial guidancetemplate and the resultant ligament tunnel and the resultant location ofthe ACL graft, once in place, may be chosen so that the graft willneither abrade nor impinge against the medial aspect of the lateralfemoral condyle or the roof of the intercondylar notch when the knee is,for example, in full extension. In this manner, highly accurate graftplacement is possible thereby avoiding the problems of impingement andsubsequent graft failure.

In another embodiment, the pre-operative scan can be evaluated todetermine the maximal possible graft length, for example, patella tendongraft. If there is concern that the maximal graft length is notsufficient for the intended ACL replacement, the tunnel location andorientation, specifically the exits from the femur or the tibia can bealtered and optimized in order to match the graft length with the tunnellength and intra-articular length.

In one embodiment, the graft length is measured or simulatedpre-operatively, for example, by measuring the optimal graft length fordifferent flexion and extension angles. Using this approach, an optimalposition, shape, orientation and design of the 3D guidance template maybe derived at an optimal compromise between isometric graft placement,avoidance of impingement onto the PCL, and/or avoidance of impingementonto the femoral condyle, maximizing achievable graft lengths.

Intraoperatively, the femoral and/or tibial 3D guidance templates mayinclude adjustment means. These adjustment means can, for example, allowmovement of the template by one or two or more millimeters intervals inposterior or medial or lateral orientation, with resultant movement ofthe femoral or tibial tunnel. Additionally, intraoperative adjustmentmay also allow for rotation of the template, with resultant rotation ofthe resultant femoral or tibial tunnels.

A single template may be utilized to derive the femoral tunnel. A singletemplate may also be utilized to derive the tibial tunnel. More than onetemplate may be used on either side.

Optionally, the templates may include linkages, for example, forattaching additional measurement devices, guide wires, or other surgicalinstruments. Alignment guides including mechanical, electrical oroptical devices may be attached or incorporated in this manner.

In another embodiment, the opposite articular surface may be crossreferenced against a first articular surface. For example, in the caseof an ACL repair, the femoral tunnel may be prepared first using a 3Dguidance template, whereby the 3D guidance template helps determine theoptimal femoral tunnel position, location, orientation, diameter, andshape. The femoral guidance template may include a link inferiorly tothe tibia or an attachable linkage, wherein said link or said attachablelinkage may be utilized to determine the ideal articular entry point forthe tibial tunnel. In this manner, the tibial tunnel can be created inan anatomic environment and in mechanical cross reference with thefemoral tunnel. The reverse approach is possible, whereby the tibialtunnel is created first using the 3D guidance template with a link orlinkage to a subsequently created femoral tunnel. Creating the femoralor tibial tunnel in reference to each other advantageously helps reducethe difficulty in performing the ligament repair and also can improvethe accuracy of the surgery in select clinical situations.

In another embodiment, the template for ligament repair may includeexterior anatomical reliefs such as optional flanges or extenders. Theseflanges or extenders may have the function of tissue retractors. Byhaving tissue retractor function, the intra-articular template forligament repair can provide the surgeon with a clearer entry to theintended site of surgical intervention and improve visualization.Moreover, flanges or extenders originating from or attached to the 3Dguidance templates may also serve as tissue protectors, for example,protecting the posterior cruciate ligament, the articular cartilage, orother articular structures as well as extra-articular structures.

In another embodiment, an additional 3D guidance template or linkages toa first or second articular 3D guidance templates can be utilized toplace ligament attachment means, for example, interference screws.

If an allograft is chosen and the allograft length and optionally,dimensions are known pre-operatively, additional adjustments may be madeto the position, shape and orientation of the 3D guidance templates andadditional tunnels in order to match graft dimensions with tunneldimensions and graft length with intra-femoral tunnel length,intra-articular length and intra-tibial tunnel length. Optionally, thisadjustment and optimization can be performed for different pose anglesof the joint, e.g. different degrees of flexion or extension.

FIGS. 30A-C illustrate an exemplary use of 3D guidance templates forperforming ligament repair; in this case repair of the anterior cruciateligament (ACL). A 3D guidance template 4000 is placed in theintercondylar notch region 4005. At least one surface 4010 of thetemplate 4000 is a mirror and/or negative image of at least portions ofthe notch 4005 or the femur. The template 4000 may be optionally placedagainst the trochlea and/or the femoral condyle (not shown). The mold4000 includes an opening 4020 and, optionally, metal sleeves 4030,wherein the position, location and orientation of the opening 4020and/or the metal sleeves 4030 determine the position and orientation ofthe femoral graft tunnel 4040.

A tibial template 4050 may be used to determine the location andorientation of the tibial tunnel 4060. Specifically, an opening 4065within the tibial mold 4050 will determine the position, angle andorientation of the tibial tunnel 4060. The opening may include optionalmetal sleeves 4068. At least one surface 4070 of the tibial template4050 will substantially match the surface of the tibia 4075. Thetemplate may be matched to a tibial spine 4080 wherein the tibial spinecan help identify the correct position of the mold and help fix thetemplate in place during the surgical intervention. Of note, the sleeves4030 and 4068 may be made of other hard materials, e.g. ceramics. Thefemoral and/or tibial template may be optionally attached to the femoralor tibial articular surface during the procedure, for example usingK-wires or screws.

FIG. 30C shows a top view of the tibial plateau 4085. The PCL 4086 isseen as are the menisci 4087. The original site of ACL attachment 4090is shown. The intended tunnel site 4092 may be slightly posterior to theoriginal ACL attachment 4090. The template 4095 may placed over theintended graft tunnel 4092. The template will typically have a perimeterslightly greater than the intended tunnel site. The templates may allowfor attachments, linkages or handles.

PCL Repair

All of the embodiments described above may also be applied to PCL repairas well as the repair of other ligaments or tendons.

For PCL repair, 3D guidance templates may be designed for single, aswell as double bundle surgical technique. With single bundle surgicaltechnique, a 3D guidance template may be created with a position,orientation and shape of the template or associated reference points orguide apertures for surgical instruments that will help create a femoraltunnel in the location of the anatomic origin of the ligament.Alternatively, the template and any related reference points or guideapertures or linkages may be designed and placed so that an anteriorplacement of the femoral tunnel in the anatomic footprint is performed.A more anterior placement of the femoral tunnel can restore normal kneelaxity better than isometric graft placement. The 3D guidance templatesmay be designed so that optimal tension is achieved not only in kneeextension but also in knee flexion, particularly ninety degrees of kneeflexion. Thus, the origin and the insertion of the PCL may be identifiedpre-operatively on the scan, either by identifying residual fiberbundles or by identifying the underlying anatomic landmarks. Thedistance between the origin and the insertion may thus be determined inthe extension and can be simulated for different flexion degrees orother articular positions. Femoral and tibial tunnel placement andorientation may then be optimized in order to achieve an isometric ornear isometric ligament placement. Intraoperative adjustments arefeasible as described in the foregoing embodiments.

A 3D guidance template may also be designed both on the femoral as wellas on the tibial side using double bundle reconstruction techniques.With double bundle reconstruction techniques, the femoral or tibialtemplate can include or incorporate links or can have attachablelinkages so that a femoral tunnel can be created and cross referencedwith a tibial tunnel, or a tibial tunnel can be created and crossreferenced to a femoral tunnel.

As described for the ACL, the templates may include stops for drills andreaming devices or other surgical instruments, for example, to protectpopliteal neurovascular structures. The templates may include extendersor flanges to serve as tissue retractors as well as tissue protectors.

In principle, templates may be designed to be compatible with anydesired surgical technique. In the case of PCL repair, templates may bedesigned to be compatible with single bundle, or a double bundlereconstruction, tibial inlay techniques as well as other approaches.

As previously stated, 3D guidance templates are applicable to any typeof ligament or tendon repair and can provide reproducible, simpleintraoperative location of intended attachment sites or tunnels. Theshape, orientation and position of the 3D guidance templates may beindividualized and optimized for articular anatomy, as well as thebiomechanical situation, and may incorporate not only the articularshape but also anatomic lines, anatomic planes, biomechanical lines orbiomechanical planes, as well as portions or all of the shape of devicesor anchors or instruments to be implanted or to be used duringimplantation or to be used during surgical repair of a ligament ortendon tear.

iii. Impingement Syndromes, Removal of Exophytic Bone Growth IncludingOsteophytes

3D guidance templates may also be utilized to treat impingementsyndromes, for example, by template guided removal of osteophytes orexophytic bone growth. In one embodiment, an imaging test such as a CTscan or an MRI scan is obtained through the area of concern. If a jointis imaged, the images can demonstrate an osteophyte or, more generally,exophytic bone growth in intra and extra-articular locations. The scandata may then be utilized to design a template having one or moreanatomical relief surfaces that match, substantially match, overlayand/or are recessed from the surface adjacent to the exophytic bonegrowth or osteophyte, the surface overlying the exophytic bone growth orosteophyte or both or portions of one or both. The template may haveopenings or apertures or linkages that allow placement of surgical toolsfor removal of the exophytic bone growth or the osteophyte, such asreamers, drills, rotating blades and the like. Someone skilled in theart will recognize many different surgical instruments that can beutilized in this manner.

Two representative examples where a 3D guidance template can be appliedto treat local impingement syndromes are the pincer and Cam impingementsyndromes in the hip joint. Pincer and Cam impingement representfemoro-acetabular impingement syndromes caused by an abutment betweenthe proximal femur and the acetabular rim during the end range ofmotion. Untreated femoral-acetabular impingement can causeosteoarthritis of the hip.

In Cam impingement, a non-spherical portion of the femoral head,typically located near the head-neck junction, is jammed into theacetabulum during hip joint motion. The Cam impingement can lead toconsiderable shear forces and subsequently chondral erosion.

In one embodiment, an imaging test, such as a CT scan or MRI scan may beperformed pre-operatively. The imaging test may be used to identify thenon-spherical portion of the femoral head at the head-neck junction thatis responsible for the impingement. A 3D guidance template may bedesigned that can be applied intraoperatively to this region. Thetemplate is designed to fulfill three principle functions:

1. Intraoperative highly accurate identification of the non-sphericalportion of the femoral head by placement of the individualized portionof the 3D template onto the area or immediately adjacent to the area.

2. Guidance of surgical instrumentation to remove the non-sphericalportion and to re-establish a spherical or essentially spherical shape.

3. Control of the depth of the bone removal and the shape of the boneremoval. For this purpose, a stop may be incorporated into the design ofthe 3D guidance template. Of note, the stop may be asymmetrical and caneven be designed to be a mirror and/or negative image of the desiredarticular contour.

FIG. 31 shows an example of treatment of CAM impingement using a 3Dguidance template 4100. The impinging area 4105 may be removed with asaw (not shown) inserted into the guide aperture 4110. The guideaperture may be designed and placed so that only the impinging portionof the joint is removed.

In Pincer impingement, linear bony contact occurs between the normalfemoral head-neck junction and enlarged or hypertrophied portion of theacetabulum. Pre-operatively an imaging test may be performed in order toidentify the abnormal, over covered or enlarged area of the acetabulum.The amount of bone removal may be determined on the imaging study, e.g.a CT scan or MRI scan. A 3D guidance template may then be designed thatwill achieve the identical three functions described above in Camimpingement.

FIG. 32 shows an example of treatment of Pincer impingement using a 3Dguidance template 4200. The impinging area 4205 may be removed with asaw (not shown) inserted into the guide aperture 4210. The guideaperture may be designed and placed so that only the impinging portionof the joint is removed.

Accurate and reproducible identification of the abnormal bony surfacecausing the impingement is critical in any form of musculoskeletalimpingement syndrome. 3D guidance template systems are ideally suited toachieve this purpose and to guide the surgical instrumentation forremoval of the source of impingement. Moreover, since the localizationof the impinging area is performed pre-operatively during the imagingtest, and intra-operatively using the 3D guidance template, thisapproach allows for minimally invasive, tissue, specifically musclesparing approaches.

iv. Surgical Navigation and 3D Guidance Templates

3D guidance template technology as described herein may be combined withsurgical navigation techniques. Surgical navigation techniques may beimage guided or non-image guided for this purpose. Passive or activesurgical navigation systems may be employed. Surgical navigation systemsthat use optical or radiofrequency transmission or registration may beused. A representative example is the Vector Vision navigation systemmanufactured by Brain Lab, Germany. This is a passive infrarednavigation system. Once the patient is positioned appropriately in theoperating room, retro-reflective markers can be applied to the extremitynear the area of intended surgery. With image guided navigation, animaging study such as a CT scan or MRI scan, can be transferred into theworkstation of the navigation system. For registration purposes, thesurgeon can, for example, utilize a pointer navigation tool to touchfour or more reference points that are simultaneously co-identified andcross registered on the CT or MRI scan on the workstation. In the kneejoint, reference points may include the trochlear groove, the mostlateral point of the lateral condyle, the most medial femoral condyle,the tip of the tibial spines and so forth. Using image guidednavigation, anatomical and biomechanical axis of the joint can bedetermined reliably.

Alternatively, non-image guided navigation may be utilized. In thiscase, retro-reflective markers or small radio frequency transmitters arepositioned on the extremity. Movement of the extremity and of the jointsis utilized, for example, to identify the center of rotation. If surgeryof the knee joint is contemplated, the knee joint may be rotated aroundthe femur. The marker or radiofrequency transmitter motion may beutilized to identify the center of the rotation, which will coincidewith the center of the femoral head. In this manner, the biomechanicalaxis may be determined non-invasively.

The information resulting in imaging guided navigation, pertaining toeither anatomical or biomechanical axis can be may be utilized tooptimize the position of any molds, blocks, linkages or surgicalinstruments attached to or guided through the 3D guidance molds.

In one embodiment, the joint or more specifically the articular surface,may be scanned intra-operatively, for example, using ultrasound oroptical imaging methods. The optical imaging methods may includestereographic or stereographic like imaging approaches, for example,multiple light path stereographic imaging of the joint and the articularsurface or even single light path 3D optical imaging. Other scantechnologies that are applicable are, for example, C-arm mountedfluoroscopic imaging systems that can optionally also be utilized togenerate cross-sectional images such as a CT scan. Intraoperative CTscanners are also applicable. Utilizing the intraoperative scan, a pointcloud of the joint or the articular surface or a 3D reconstruction or a3D visualization and other 3D representations may be generated that canbe utilized to generate an individualized template wherein at least aportion of said template includes a surface that is a mirror and/ornegative image of the joint or the articular surface. A rapidprototyping or a milling or other manufacturing machine can be availablein or near the operating room and the 3D guidance template may begenerated intraoperatively.

The intraoperative scan in conjunction with the rapid production of anindividualized 3D guidance template matching the joint or the articularsurface, in whole or at least in part, has the advantage to generaterapidly a tool for rapid intraoperative localization of anatomicallandmarks, including articular landmarks. A 3D guidance template maythen optionally be cross-registered, for example, using optical markersor radiofrequency transmitters attached to the template with thesurgical navigation system. By cross-referencing the 3D guidancetemplate with the surgical navigation system, surgical instruments cannow be reproducibly positioned in relationship to the 3D guidancetemplate to perform subsequent procedures in alignment with or in adefined relationship to at least one or more anatomical axis and/or atleast one or more biomechanical axis or planes.

v. Stereoscopy, Stereoscopic Imaging:

In addition to cross-sectional or volumetric imaging technologiesincluding CT, spiral CT, and MRI, stereoscopic imaging modalities may beutilized. Stereoscopic imaging is any technique capable of recordingthree-dimensional information from two two-dimensional, projectionalimaging. Traditional stereoscopic imaging includes creating a 3Dvisualization or representation starting from a pair of 2D images. Theprojection path of the 2D images is offset. The offset is, for example,designed to create an impression of object depth for the eyes of theviewer. The offset or minor deviation between the two images is similarto the prospectors that both eyes naturally receive inbinocular vision.Using two or more images with an offset or minor deviation inperspective, it is possible to generate a point cloud or 3D surface or3D visualization of a joint or an articular surface, which can then beinput into a manufacturing system such as a rapid prototyping or millingmachine. Dual or more light path, as well as single light path, systemscan be employed

vi. Knee Joint

When a total knee arthroplasty is contemplated, the patient can undergoan imaging test, as discussed in more detail above, that willdemonstrate the articular anatomy of a knee joint, e.g. width of thefemoral condyles, the tibial plateau etc. Additionally, other joints canbe included in the imaging test thereby yielding information on femoraland tibial axes, deformities such as varus and valgus and otherarticular alignment. The imaging test can be an x-ray image, includingin a standing, load-bearing position, a CT or spiral CT scan or an MRIscan or combinations thereof. A spiral CT scan may be advantageous overa standard CT scan due to its improved spatial resolution in z-directionin addition to x and y resolution. The articular surface and shape aswell as alignment information generated with the imaging test can beused to shape the surgical assistance device, to select the surgicalassistance device from a library of different devices with pre-madeshapes and sizes, or can be entered into the surgical assistance deviceand can be used to define an optimal location and orientation of sawguides or drill holes or guides for reaming devices or other surgicalinstruments. Intraoperatively, the surgical assistance device is appliedto the tibial plateau and subsequently the femoral condyle(s) bymatching its surface with the articular surface or by attaching it toanatomic reference points on the bone or cartilage. The surgeon can thenintroduce a reamer or saw through the guides and prepare the joint forthe implantation. By cutting the cartilage and bone along anatomicallydefined planes, a more reproducible placement of the implant can beachieved. This can ultimately result in improved postoperative resultsby optimizing biomechanical stresses applied to the implant andsurrounding bone for the patient's anatomy and by minimizing axismalalignment of the implant. In addition, the surgical assistance devicecan greatly reduce the number of surgical instruments needed for totalor unicompartmental knee arthroplasty. Thus, the use of one or moresurgical assistance devices can help make joint arthroplasty moreaccurate, improve postoperative results, improve long-term implantsurvival, reduce cost by reducing the number of surgical instrumentsused. Moreover, the use of one or more surgical assistance device canhelp lower the technical difficulty of the procedure and can helpdecrease operating room (“OR”) times.

Thus, surgical tools described herein can also be designed and used tocontrol drill alignment, depth and width, for example when preparing asite to receive an implant. For example, the tools described herein,which typically conform to the joint surface, can provide for improveddrill alignment and more accurate placement of any implant. Ananatomically correct tool can be constructed by a number of methods andcan be made of any material, including a substantially translucentand/or transparent material such as plastic, Lucite, silastic, SLA orthe like, and typically is a block-like shape prior to molding.

FIG. 14 A depicts, in cross-section, an example of a mold 600 for use onthe tibial surface having an upper surface 620. The mold 600 contains anaperture 625 through which a surgical drill or saw can fit. The apertureguides the drill or saw to make the proper hole or cut in the underlyingbone 610 as illustrated in FIGS. 11 B-D. Dotted lines 632 illustratewhere the cut corresponding to the aperture will be made in bone.

FIG. 14 B depicts, a mold 608 suitable for use on the femur. As can beappreciated from this perspective, additional apertures are provided toenable additional cuts to the bone surface. The apertures 605 enablecuts 606 to the surface of the femur. The resulting shape of the femurcorresponds to the shape of the interior surface of the femoral implant,typically as shown in FIG. 11E. Additional shapes can be achieved, ifdesired, by changing the size, orientation and placement of theapertures. Such changes would be desired where, for example, theinterior shape of the femoral component of the implant requires adifferent shape of the prepared femur surface.

Turning now to FIG. 15, a variety of illustrations are provided showinga tibial cutting block and mold system. FIG. 15A illustrates the tibialcutting block 2300 in conjunction with a tibia 2302 that has not beenresected. In this depiction, the cutting block 2300 consists of at leasttwo pieces. The first piece is a patient specific interior piece 2310 ormold that is designed on its inferior surface 2312 to mate, orsubstantially mate, with the existing geography of the patient's tibia2302. The superior surface 2314 and side surfaces 2316 of the firstpiece 2310 are configured to mate within the interior of an exteriorpiece 2320. The reusable exterior piece 2320 fits over the interiorpiece 2310. The system can be configured to hold the mold onto the bone.

The reusable exterior piece has a superior surface 2322 and an inferiorsurface 2324 that mates with the first piece 2310. The reusable exteriorpiece 2320 includes cutting guides 2328, to assist the surgeon inperforming the tibial surface cut described above. As shown herein aplurality of cutting guides can be provided to provide the surgeon avariety of locations to choose from in making the tibial cut. Ifnecessary, additional spacers can be provided that fit between the firstpatient configured, or molded, piece 2310 and the second reusableexterior piece, or cutting block, 2320.

If desired, the mold may be a single component or multiple components.In one embodiment, one or more components are patient specific whileother components such as spacers or connectors to surgical instrumentsare generic. In one embodiment, the mold can rest on portions of thejoint on the articular surface or external to the articular surface.Other surgical tools then may connect to the mold. For example, astandard surgical cut block as described for standard implants, forexample in the knee the J&J PFC Sigma system, the Zimmer Nexgen systemor the Stryker Duracon system, can be connected or placed on the mold.In this manner, the patient specific component can be minimized and canbe made compatible with standard surgical instruments.

The mold may include receptacles for standard surgical instrumentsincluding alignment tools or guides. For example, a tibial mold for usein knee surgery may have an extender or a receptacle or an opening toreceive a tibial alignment rod. In this manner, the position of the moldcan be checked against the standard alignment tools and methods.Moreover, the combined use of molds and standard alignment toolsincluding also surgical navigation techniques can help improve theaccuracy of or optimize component placement in joint arthroplasty, suchas hip or knee arthroplasty. For example, the mold can help define thedepth of a horizontal tibial cut for placement of a tibial component. Atibial alignment guide, for example an extramedullary or intramedullaryalignment guide, used in conjunction with a tibial mold can help findthe optimal anteroposterior angulation, posterior slope, tibial slant,or varus-valgus angle of the tibial cut. The mold may be designed towork in conjunction with traditional alignment tools known in the art.

The mold may include markers, e.g. optoelectronic or radiofrequency, forsurgical navigation. The mold may have receptacles to which such markerscan be attached, either directly or via a linking member.

The molds can be used in combination with a surgical navigation system.They can be used to register the bones associated with a joint into thecoordinate system of the surgical navigation system. For example, if amold for a joint surface includes tracking markers for surgicalnavigation, the exact position and orientation of the bone can bedetected by the surgical navigation system after placement of the moldin its unique position. This helps to avoid the time-consuming processto acquire the coordinates of tens to hundreds of points on the jointsurface for registration.

Referring back to FIG. 15A, the variable nature of the interior piecefacilitates obtaining the most accurate cut despite the level of diseaseof the joint because it positions the exterior piece 2320 such that itcan achieve a cut that is perpendicular to the mechanical axis. Eitherthe interior piece 2310 or the exterior piece 2320 can be formed out ofany suitable material. Additionally, it should be understood that thevarious embodiments described herein may be of a single piececonfiguration as the two or more piece configuration described herein.The reusable exterior piece 2320 and the patient specific interior piece2310 can be a single piece that is either patient specific (wheremanufacturing costs of materials support such a product) or is reusablebased on a library of substantially defect conforming shapes developedin response to known or common tibial surface sizes and defects.

The interior piece 2310 is typically molded to the tibia including thesubchondral bone and/or the cartilage, as well as including one or moreanatomical relief surfaces (not shown), if desired. The surgeon willtypically remove any residual meniscal tissue prior to applying themold. Optionally, the interior surface 2312 of the mold can includeshape information of portions or all of the menisci.

Turning now to FIG. 15 B-D, a variety of views of the removable exteriorpiece 2320. The top surface 2322 of the exterior piece can be relativelyflat. The lower surface 2324 which abuts the interior piece conforms tothe shape of the upper surface of the interior piece. In thisillustration the upper surface of the interior piece is flat, thereforethe lower surface 2324 of the reusable exterior surface is also flat toprovide an optimal mating surface.

A guide plate 2326 is provided that extends along the side of at least aportion of the exterior piece 2320. The guide plate 2326 provides one ormore slots or guides 2328 through which a saw blade can be inserted toachieve the cut desired of the tibial surface. Additionally, the slot,or guide, can be configured so that the saw blade cuts at a lineperpendicular to the mechanical axis, or so that it cuts at a line thatis perpendicular to the mechanical axis, but has a 4-7° slope in thesagittal plane to match the normal slope of the tibia.

Optionally, a central bore 2330 can be provided that, for example,enables a drill to ream a hole into the bone for the stem of the tibialcomponent of the knee implant.

FIGS. 15 E-H illustrate the interior, patient specific, piece 2310 froma variety of perspectives. FIG. 15 E shows a side view of the pieceshowing the uniform superior surface 2314 and the uniform side surfaces2316 along with the irregular inferior surface 2316. The inferiorsurface mates with the irregular surface of the tibia 2302. FIG. 15 Fillustrates a superior view of the interior, patient, specific piece ofthe mold 2310. Optionally having an aperture 2330. FIG. 15 G illustratesan inferior view of the interior patient specific mold piece 2310further illustrating the irregular surface which includes convex andconcave portions to the surface, as necessary to achieve optimal matingwith the surface of the tibia. FIG. 15 H illustrates cross-sectionalviews of the interior patient specific mold piece 2310. As can be seenin the cross-sections, the surface of the interior surface changes alongits length.

As is evident from the views shown in FIGS. 15 B and 15 D, the length ofthe guide plate 2326 can be such that it extends along all or part ofthe tibial plateau, e.g. where the guide plate 2326 is asymmetricallypositioned as shown in FIG. 15 B or symmetrically as in FIG. 15 D. Iftotal knee arthroplasty is contemplated, the length of the guide plate2326 typically extends along all of the tibial plateau. Ifunicompartmental arthroplasty is contemplated, the length of the guideplate typically extends along the length of the compartment that thesurgeon will operate on. Similarly, if total knee arthroplasty iscontemplated, the length of the molded, interior piece 2310 typicallyextends along all of the tibial plateau; it can include one or bothtibial spines. If unicompartmental arthroplasty is contemplated, thelength of the molded interior piece typically extends along the lengthof the compartment that the surgeon will operate on; it can optionallyinclude a tibial spine.

Turning now to FIG. 151, an alternative embodiment is depicted of theaperture 2330. In this embodiment, the aperture features lateralprotrusions to accommodate using a reamer or punch to create an openingin the bone that accepts a stem having flanges.

FIGS. 15 J and 15 M depict alternative embodiments designed to controlthe movement and rotation of the cutting block 2320 relative to the mold2310. As shown in FIG. 15 J a series of protrusions, illustrated as pegs2340, are provided that extend from the superior surface of the mold. Aswill be appreciated by those of skill in the art, one or more pegs orprotrusions can be used without departing from the scope of theinvention. For purposes of illustration, two pegs have been shown inFIG. 15 J. Depending on the control desired, the pegs 2340 areconfigured to fit within, for example, a curved slot 2342 that enablesrotational adjustment as illustrated in FIG. 15 K or within a recess2344 that conforms in shape to the peg 2340 as shown in FIG. 15 L. Aswill be appreciated by those of skill in the art, the recess 2344 can besized to snugly encompass the peg or can be sized larger than the peg toallow limited lateral and rotational movement. The recess can becomposed of a metal or other hard insert 544.

As illustrated in FIG. 15M the surface of the mold 2310 can beconfigured such that the upper surface forms a convex dome 2350 thatfits within a concave well 2352 provided on the interior surface of thecutting block 2320. This configuration enables greater rotationalmovement about the mechanical axis while limiting lateral movement ortranslation.

Other embodiments and configurations could be used to achieve theseresults without departing from the scope of the invention.

As will be appreciated by those of skill in the art, more than twopieces can be used, where appropriate, to comprise the system. Forexample, the patient specific interior piece 2310 can be two pieces thatare configured to form a single piece when placed on the tibia.Additionally, the exterior piece 2320 can be two components. The firstcomponent can have, for example, the cutting guide apertures 2328. Afterthe resection using the cutting guide aperture 2328 is made, theexterior piece 2320 can be removed and a secondary exterior piece 2320′can be used which does not have the guide plate 2326 with the cuttingguide apertures 2328, but has the aperture 2330 which facilitates boringinto the tibial surface an aperture to receive a stem of the tibialcomponent of the knee implant. Any of these designs could also featurethe surface configurations shown in FIGS. 15 J-15 M, if desired.

FIG. 15 N illustrates an alternative design of the cutting block 2320that provides additional structures 2360 to protect, for example, thecruciate ligaments, from being cut during the preparation of the tibialplateau. These additional structures can be in the form of indentedguides 2360, as shown in FIG. 15 N or other suitable structures,including other types of external anatomical relief surfaces.

FIG. 15 O illustrates a cross-section of a system having anchoring pegs2362 on the surface of the interior piece 2310 that anchor the interiorpiece 2310 into the cartilage or meniscal area.

FIGS. 15 P AND 15 Q illustrate a device 2300 configured to cover half ofa tibial plateau such that it is unicompartmental.

FIG. 15 R illustrates an interior piece 2310 that has multiple contactsurfaces 2312 with the tibial 2302, in accordance with one embodiment.As opposed to one large contact surface, the interior piece 2310includes a plurality of smaller contact surfaces 2312 separated by oneor more anatomical relief surfaces. In various embodiments, the multiplecontact surfaces 2312 are not on the sample plane and are at anglesrelative to each other to ensure proper positioning on the tibia 2302.Two or three contact surfaces 2312 may be desirable to ensure properpositioning. In various embodiments, only the contact surfaces 2312 ofthe interior piece may be molded, the molds attached to the rest of thetemplate using methodologies known in the art, such as adhesives. Themolds may be removably attached to the template. It is to be understoodthat multiple contact surfaces 2312 may be utilized in templateembodiments that include one or a plurality of pieces.

Turning now to FIG. 16, a femoral mold system is depicted thatfacilitates preparing the surface of the femur such that the finallyimplanted femoral implant will achieve optimal mechanical and anatomicalaxis alignment.

FIG. 16A illustrates the femur 2400 with a first portion 2410 of themold placed thereon. In this depiction, the top surface of the mold 2412is provided with a plurality of apertures. In this instance theapertures consist of a pair of rectangular apertures 2414, a pair ofsquare apertures 2416, a central bore aperture 2418 and a longrectangular aperture 2420. The side surface 2422 of the first portion2410 also has a rectangular aperture 2424. Each of the apertures islarger than the eventual cuts to be made on the femur so that, in theevent the material the first portion of the mold is manufactured from asoft material, such as plastic, it will not be inadvertently cut duringthe joint surface preparation process. Additionally, the shapes can beadjusted, e.g., rectangular shapes made trapezoidal, to give a greaterflexibility to the cut length along one area, without increasingflexibility in another area. As will be appreciated by those of skill inthe art, other shapes for the apertures, or orifices, can be changedwithout departing from the scope of the invention.

FIG. 16 B illustrates a side view of the first portion 2410 from theperspective of the side surface 2422 illustrating the aperture 2424. Asillustrated, the exterior surface 2411 has a uniform surface which isflat, or relatively flat configuration while the interior surface 2413has an irregular surface that conforms, or substantially conforms, withthe surface of the femur.

FIG. 16 C illustrates another side view of the first, patient specificmolded, portion 2410, more particularly illustrating the irregularsurface 2413 of the interior. FIG. 16 D illustrates the first portion2410 from a top view. The center bore aperture 2418 is optionallyprovided to facilitate positioning the first piece and to preventcentral rotation.

FIG. 16 D illustrates a top view of the first portion 2410. The bottomof the illustration corresponds to an anterior location relative to theknee joint. From the top view, each of the apertures is illustrated asdescribed above. As will be appreciated by those of skill in the art,the apertures can be shaped differently without departing from the scopeof the invention.

Turning now to FIG. 16 E, the femur 2400 with a first portion 2410 ofthe cutting block placed on the femur and a second, exterior, portion2440 placed over the first portion 2410 is illustrated. The second,exterior, portion 2440 features a series of rectangular grooves(2442-2450) that facilitate inserting a saw blade therethrough to makethe cuts necessary to achieve the femur shape illustrated in FIG. 11 E.These grooves can enable the blade to access at a 90° angle to thesurface of the exterior portion, or, for example, at a 45° angle. Otherangles are also possible without departing from the scope of theinvention.

As shown by the dashed lines, the grooves (2442-2450) of the secondportion 2440, overlay the apertures of the first layer.

FIG. 16 F illustrates a side view of the second, exterior, cutting blockportion 2440. From the side view a single aperture 2450 is provided toaccess the femur cut. FIG. 16 G is another side view of the second,exterior, portion 2440 showing the location and relative angles of therectangular grooves. As evidenced from this view, the orientation of thegrooves 2442, 2448 and 2450 is perpendicular to at least one surface ofthe second, exterior, portion 2440. The orientation of the grooves 2444,2446 is at an angle that is not perpendicular to at least one surface ofthe second, exterior portion 2440. These grooves (2444, 2446) facilitatemaking the angled chamfer cuts to the femur. FIG. 16 H is a top view ofthe second, exterior portion 2440. As will be appreciated by those ofskill in the art, the location and orientation of the grooves willchange depending upon the design of the femoral implant and the shaperequired of the femur to communicate with the implant.

FIG. 16 I illustrates a spacer 2401 for use between the first portion2410 and the second portion 2440. The spacer 2401 raises the secondportion relative to the first portion, thus raising the area at whichthe cut through groove 2424 is made relative to the surface of thefemur. As will be appreciated by those of skill in the art, more thanone spacer can be employed without departing from the scope of theinvention. Spacers can also be used for making the tibial cuts. Optionalgrooves or channels 2403 can be provided to accommodate, for example,pins 2460 shown in FIG. 16 J.

Similar to the designs discussed above with respect to FIG. 15,alternative designs can be used to control the movement and rotation ofthe cutting block 2440 relative to the mold 2410. As shown in FIG. 16 Ja series of protrusions, illustrated as pegs 2460, are provided thatextend from the superior surface of the mold. These pegs or protrusionscan be telescoping to facilitate the use of molds if necessary. As willbe appreciated by those of skill in the art, one or more pegs orprotrusions can be used without departing from the scope of theinvention. For purposes of illustration, two pegs have been shown inFIG. 16 J. Depending on the control desired, the pegs 2460 areconfigured to fit within, for example, a curved slot that enablesrotational adjustment similar to the slots illustrated in FIG. 15 K orwithin a recess that conforms in shape to the peg, similar to that shownin FIG. 15 L and described with respect to the tibial cutting system. Aswill be appreciated by those of skill in the art, the recess 2462 can besized to snugly encompass the peg or can be sized larger than the peg toallow limited lateral and rotational movement.

As illustrated in FIG. 16 K the surface of the mold 2410 can beconfigured such that the upper surface forms a convex dome 2464 thatfits within a concave well 2466 provided on the interior surface of thecutting block 2440. This configuration enables greater rotationalmovement about the mechanical axis while limiting lateral movement ortranslation.

In installing an implant, first the tibial surface is cut using a tibialblock, such as those shown in FIG. 16. The patient specific mold isplaced on the femur. The knee is then placed in extension and spacers2401, such as those shown in FIG. 16M, or shims are used, if required,until the joint optimal function is achieved in both extension andflexion. The spacers, or shims, are typically of an incremental size,e.g., 5 mm thick to provide increasing distance as the leg is placed inextension and flexion. A tensiometer can be used to assist in thisdetermination or can be incorporated into the mold or spacers in orderto provide optimal results. The design of tensiometers are known in theart and are not specifically described herein. Suitable designs include,for example, those described in U.S. Pat. No. 5,630,820 to Todd issuedMay 20, 1997.

As illustrated in FIGS. 16 N (sagittal view) and 26O (coronal view), theinterior surface 2413 of the mold 2410 can include small teeth 2465 orextensions that can help stabilize the mold against the cartilage 2466or subchondral bone 2467.

3D guidance templates may be used to create more that one cut on thesame and/or on the opposite articular surface or opposite articularbone, in accordance with an embodiment. These cuts may becross-referenced with other cuts using one or more guidance template(s).

In accordance with one embodiment, the 3D guidance template(s) areutilized to perform more than one cut on the same articular side such asthe femoral side of a knee joint. In another embodiment, a 3D guidancetemplate may be utilized to cross reference surgical interventions on anopposing articular surface. In a knee, for example, the first articularsurface can be the femoral surface. The opposing articular surface canbe the tibial surface or the patella surface. In a hip, the firstarticular surface can be the acetabulum. The opposing articular surfaceor the opposing bone can be the proximal femur.

Thus, in a knee, a horizontal femur cut can be cross-referenced with ananterior or posterior femur cut or optionally also chamfer, obliquecuts. Similarly, a tibial horizontal cut can be cross-referenced withany tibial oblique or vertical cuts on the same articular side orsurface.

In accordance with another embodiment, one or more femur cuts can becrossed-referenced with one or more tibial cuts. Or, in a hip, one ormore acetabular cuts or surgical interventions can be cross-referencedwith one or more femoral cuts or surgical interventions such asdrilling, reaming or boring. Similarly, in a knee again, one or morefemur cuts can be cross-referenced with one or more patella cuts. Anycombination and order is possible.

The cross-referencing can occur via attachments or linkages includingspacers or hinge or ratchet like devices from a first articular boneand/or cartilage surface, to a second articular, bone and/or cartilagesurface. The resulting positioning of the cut on the opposing articular,bone or cartilage surface can be optimized by testing the cut formultiple pose angles or joint positions such as flexion, extension,internal or external rotation, abduction or adduction. Thus, forexample, in a knee a distal femur cut can be performed with a mold. Viaa linkage or an attachment, a tibial template may be attached thereto orto the cut or other surgical intervention, thus a cross-reference can berelated from the femoral cut to a tibial cut or other surgicalintervention. Cross-referencing from a first articular surface to asecond articular surface via, without limitation, attachments orlinkages to a template has the advantage of insuring an optimalalignment between the implant or other therapeutic device components ofthe first articular surface to that on a second articular surface.Moreover, by cross-referencing surgical interventions on a firstarticular surface to a second articular surface, improved efficienciesand time savings can be obtained with the resulted surgical procedure.

Cross-referencing the first, the second and, optionally a third or morearticular surface, such as in a knee joint, may be performed with asingle linkage or attachment or multiple linkages or attachments. Asingle pose angle or position of a joint or multiple pose angles orpositions of a joint may be tested and optimized during the entiresurgical intervention. Moreover, any resulting surgical interventions onthe opposite, second articular surface, bone or cartilage may be furtheroptimized by optionally cross-referencing to additional measurementtools such as standard alignment guides.

For example, in a knee joint, a 3D template may be utilized to performone or more surgical interventions on the femoral side, such as afemoral cut. This can then be utilized via a linkage, an attachment orvia indirect cross-referencing directly onto the site of surgicalintervention, to guide a surgical intervention such as a cut of thetibial side. Prior to performing the surgical intervention on the tibialside, a traditional tibial alignment guide with cross-reference to themedial and lateral malleolus of the ankle turn may be used to optimizethe position, orientation and/or depth and extent of the plannedsurgical intervention such as the cut. For example, cross-referencing tothe femoral cut can aid in defining the relative superior inferiorheight of the tibial cut, while cross-referencing a tibial alignmentguide can optionally be utilized to determine the slant of the cut inthe interior posterior direction.

An exemplary system and methodology is now described in which a femoraltemplate is used to make a cut on the femur, which is thencross-referenced to properly align a tibial template for making a cut onthe tibial plateau. Initially, an electronic image(s) of the leg isobtained using imaging techniques elaborated in above-describedembodiments. For example, a pre-operative CT scan of a patient's leg maybe obtained to obtain electronic image data.

Image processing is then applied to the image data to derive, withoutlimitation, relevant joint surfaces, axis, and/or cut planes. Imageprocessing techniques may include, without limitation, segmentation andpropagation of point clouds.

Relevant biomechanical and/or anatomical axis data may be obtained byidentifying, for example, the central femoral head, central knee jointand center of the distal tibia. The cutting planes may then be definedbased on at least one of these axis. For example, the tibial implantbearing surface may be defined as being perpendicular to the axisdefined by the center of the tibial plateau 2496 and the center of thedistal tibia 2497, as illustrated in FIG. 16 P; the tibial implant'smedial margin may project towards the femoral head, as illustrated inFIG. 16 Q; and the anterior to posterior slope of the tibia may beapproximated by the natural anatomical slope (alternatively, excessivetibial slope may be corrected).

The tibial and femoral templates and implants may be designed based, atleast in part, on the derived joint surfaces, axis and/or cut planes.FIGS. 16 R and 16 S show isometric views of a femoral template 2470 anda tibial template 2480, respectively, in accordance with an embodiment.The femoral template 2470 has an interior surface that, in variousembodiments, conforms, or substantially conforms, with the anatomicsurface (bone and/or cartilage) of the femur 2475. Furthermore, theinterior surface of the femoral template may extend a desired amountaround the anatomical boney surfaces of the condyle to further ensureproper fixation. The interior surface of the tibial cutting block 2480may conform, or substantially conform to the surface (bone and/orcartilage) of the tibia 2481.

In an exemplary use, the femoral template 2470 is placed on the femoralcondyle 2475, for example, when the knee is flexed. The femoral template2470 may be fixed to the femoral condyle 2475 using, without limitation,anchoring screws/drill pins inserted through drill bushing holes 2471and 2472. The position of holes 2471 and 2472 on the condyle may be thesame used to anchor the final implant to the femur. In variousembodiments, the holes 2471 and 2472 may include metal inserts/bushingsto prevent degradation when drilling. Fixing the template 2470 to thefemoral condyle 2475 advantageously prevents movement of the templateduring subsequent cutting or other surgical interventions therebyensuring the accuracy of the resultant surgical cuts.

To assist in accurately positioning the femoral template 2470, a femoralguide reference tool 2473 may be attached to the femoral template 2470,as shown in FIG. 16 T. The femoral guide reference tool 2473 may,without limitation, attach to one of holes 2471 and 2472. The femoralguide reference tool 2473 may reference off the tangential margin of theposterior condyle, and aid, for example, in correct anterior-posteriorpositioning of the femoral template 2470.

Upon proper fixation of the femoral template 2470 to the femoral condyle2475, a cut to the femoral condyle is made using cut guide surface orelement 2474. The cut guide surface or element 2474 may be integral tothe femoral template 2470, or may be an attachment to the femoraltemplate 2470, with the attachment made of a harder material than thefemoral template 2470. For example, the cut guide surface or element2474 may be a metal tab that slides onto the femoral template 2470,which may be made, without limitation, of a softer, plastic material.

Upon making the femoral cut and removing the femoral template 2475, asample implant template 2476 (not the final implant) is optionallypositioned on the condyle, as shown in FIG. 16 U, in accordance with anembodiment. The sample implant template 2474 may be attached to thecondyle by using, without limitation, anchoring screws/drill pinsinserted through the same holes used to anchor the final implant to thefemur.

The sample implant template 2476 includes an attachment mechanism 2494for attaching the tibial template 2480, thereby cross-referencing theplacement of the distal tibial cut with respect to the femoralcut/implant's placement. The attachment mechanism 2494 may be, withoutlimitation, a boss, as shown in FIG. 16 U, or other attachment mechanismknown in the art, such as a snap-fit mechanism. Note that in alternativeembodiments, a sample implant template 2476 may not be required. Forexample, the tibial template 2480 may attach directly to the femoraltemplate 2470. However, in the subject embodiment, the drill bushingfeatures of the femoral template 2475 can interfere with the knee goinginto extension, possibly preventing the tibial cut.

In illustrative embodiments, the thickness of the sample implanttemplate 2476 may not only include the thickness of the final femoralimplant, but may include an additional thickness that corresponds to adesired joint space between tibial and femoral implants. For example,the additional thickness may advantageously provide a desired jointspace identified for proper ligament balancing or for flexion,extension, rotation, abduction, adduction, anteversion, retroversion andother joint or bone positions and motion.

FIG. 16 V is an isometric view of the interior surface of the sampleimplant template 2476, in accordance with an embodiment. In variousembodiments, the femoral implant can often rest on subchondral bone,with the cartilage being excised. In embodiments where the sampleimplant template 2474 extends beyond the dimensions of the femoralimplant such that portions of the sample implant template 2476 rests oncartilage, an offset 2477 in the interior surface of the sample implanttemplate 2476 may be provided.

FIG. 16 W is an isometric view of the tibial template 2480 attached tothe sample implant 2476 when the knee is in extension, in accordancewith an embodiment. A crosspin 2478 inserted through boss 2494 fixes thetibial template 2480 to the sample implant template 2474. Of course,other attachment mechanisms may be used, as described above. In variousembodiments, the tibial template 2480 may also be fixed to the tibia2481 using, without limitation, anchoring screws/drill pins insertedthrough drill bushing hole 2479. In various embodiments, the holes 2479include metal inserts (or other hard material) to prevent degradationwhen drilling. As with the femoral template 2475, the cut guide surfaceor element of the tibial template 2480 may be integral to the tibialtemplate 2475, or may be an attachment to the tibial template 2480, theattachment made of a harder material than the tibial template 2480. Uponfixing the position of the tibial template 2480, the cut guide of thetibial template 2475 assists in guiding the desired cut on the tibia.

FIG. 16 X shows a tibial template 2490 that may be used, after thetibial cut has been made, to further guide surgical tools in forminganchoring apertures in the tibia for utilization by the tibial implant(e.g., the tibial implant may include pegs and/or keels that are used toanchor the tibial implant into the tibia), in accordance with anotherembodiment. The outer perimeter of a portion of the tibial template 2490may mimic the perimeter of the tibial implant. Guide apertures in thetibial template 2490 correspond to the tibial implants fixationfeatures. A portion of the tibial template 2490 conforms to, withoutlimitation, the anterior surface of the tibia to facilitate positioningand anchoring of the template 2490.

FIG. 16 Y shows a tibial implant 2425 and femoral implant 2426 insertedonto the tibia and femur, respectively, after the above-described cutshave been made, in accordance with an embodiment.

Thus, the tibial template 2480 used on the tibia can be cross-referencedto the femoral template 2476, femoral cut and/or sample implant 2474.Similarly, in the hip, femoral templates can be placed in reference toan acetabular mold or vice versa. In general, when two or more articularsurfaces will be repaired or replaced, a template can be placed on oneor more of them and surgical procedures including cutting, drilling,sawing or rasping can be performed on the other surface or othersurfaces in reference to said first surface(s).

In illustrative embodiments, three-dimensional guidance templates may beutilized to determine an optimized implant rotation. Examples areprovided below with reference to the knee, however it is to beunderstood that optimizing implant rotation may be applied other jointsas well.

Femoral Rotation:

The optimal rotation of a femoral component or femoral implant for auni-compartmental, patello femoral replacement or total knee replacementmay be ascertained in a number of different ways. Implant rotation istypically defined using various anatomic axes or planes. These anatomicaxes may include, without limitation, the transepicondylar axis; theWhiteside line, i.e. the trochlea anteroposterior axis, which istypically perpendicular to at least one of the cuts; and/or theposterior condylar axis. Another approach for optimizing femoralcomponent rotation is a so-called balancing gap technique. With thebalancing gap technique, a femoral cut is made parallel to the tibia,i.e. the tibia is cut first typically. Prior to performing the femoralcut, the femoral cut plate is optimized so that the medial and lateralligament and soft tissue tension are approximately equal.

By measuring the relevant anatomic axis or planes, the optimal implantrotation may be determined. In various embodiments, the measurement maybe factored into the shape, position or orientation of the 3D guidancetemplate. Any resultant surgical interventions including cuts, drilling,or sawings are then made incorporating this measurement, therebyachieving an optimal femoral component rotation.

Moreover in order to achieve an optimal balancing, the rotation of thetemplate may be changed so that the cuts are parallel to the tibial cutwith substantially equal tension medially and laterally applied.

Tibial Rotation:

A 3D guidance template may also be utilized to optimize tibial componentrotation for uni-compartmental or total knee replacements, in accordancewith an embodiment. Tibial component rotation may be measured using anumber of different approaches known in the art. In one example of atibial component rotation measurement, the anteroposterior axis of thetibia is determined. For a total knee replacement, the tibial componentcan be placed so that the axis of the implant coincides with the medialone-third of the tibial tuberosity. This approach works well when thetibia is symmetrical.

In another embodiment, the symmetrical tibial component is placed as faras possible posterolateral and externally rotated so that theposteromedial corner of the tibial plateau is uncovered to an extent ofbetween three (3) and five (5) millimeters.

The above examples are only representative of the different approachesthat have been developed in the literature. Other various anatomic axis,plane and area measurements may be performed in order to optimizeimplant rotation.

In illustrative embodiments, these measurements may be factored into thedesign of a 3D guidance template and the position, shape or orientationof the 3D guidance template may be optimized utilizing this information.Thus, any subsequent surgical intervention such as cutting, sawingand/or drilling will result in an optimized implant rotation, forexample, in the horizontal or in a near horizontal plane.

Turning now to FIG. 17, a variety of illustrations are provided showinga patellar cutting block and mold system. FIGS. 17 A-17 C illustratesthe patellar cutting block 2700 in conjunction with a patella 2702 thathas not been resected. In this depiction, the cutting block 2700 canconsist of only one piece or a plurality of pieces, if desired. Theinner surface 2703 is patient specific and designed to mate, orsubstantially mate, with the existing geography of the patient's patella2702. Small openings are present 2707 to accept the saw. The mold orblock can have only one or multiple openings. The openings can be largerthan the saw in order to allow for some rotation or other fineadjustments. FIG. 17 A is a view in the sagittal plane S. The quadricepstendon 2704 and patellar tendon 2705 are shown.

FIG. 17 B is a view in the axial plane A. The cartilage 2706 is shown.The mold can be molded to the cartilage or the subchondral bone orcombinations thereof. FIG. 17 C is a frontal view F of the molddemonstrating the opening for the saw 2707. The dashed line indicatesthe relative position of the patella 2702.

FIGS. 17 D (sagittal view) and E (axial view) illustrate a patellarcutting block 2708 in conjunction with a patella 2702 that has not beenresected. In this depiction, the cutting block 2708 consists of at leasttwo pieces. The first piece is a patient specific interior piece 2710 ormold that is designed on its inferior surface 2712 to mate, orsubstantially mate, with the existing geography of the patient's patella2702, and may optionally include one or more anatomical relief surfaces2713 in areas to avoid various anatomical features (for one or morereasons) or where imaging of the anatomical structures is suboptimal oruncertain. The posterior surface 2714 and side surfaces 2716 of thefirst piece 2710 are configured to mate within the interior of anexterior piece 2720. The reusable exterior piece 2720 fits over theinterior piece 2710 and holds it onto the patella. The reusable exteriorpiece has an interior surface 2724 that mates with the first piece 2710.The reusable exterior piece 2720 includes cutting guides 2707, to assistthe surgeon in performing the patellar surface cut. A plurality ofcutting guides can be provided to provide the surgeon a variety oflocations to choose from in making the patellar cut. If necessary,additional spacers can be provided that fit between the first patientconfigured, or molded, piece 2710 and the second reusable exteriorpiece, or cutting block, 2720.

The second reusable exterior piece, or cutting block, 2720, can havegrooves 2722 and extensions 2725 designed to mate with surgicalinstruments such as a patellar clamp 2726. The patellar clamp 2726 canhave ring shaped graspers 2728 and locking mechanisms, for exampleratchet-like 2730. The opening 2732 in the grasper fits onto theextension 2725 of the second reusable exterior piece 2720. Portions of afirst portion of the handle of the grasper can be at an oblique angle2734 relative to the second portion of the handle, or curved (notshown), in order to facilitate insertion. Typically the portion of thegrasper that will be facing towards the intra-articular side will havean oblique or curved shaped thereby allowing a slightly smallerincision.

The variable nature of the interior piece facilitates obtaining the mostaccurate cut despite the level of disease of the joint because itpositions the exterior piece 2720 in the desired plane. Either theinterior piece 2710 or the exterior piece 2720 can be formed out of anyof the materials discussed above in Section II, or any other suitablematerial. Additionally, it should be understood that that the variousembodiments described herein may include one, two or more piececonfigurations. The reusable exterior piece 2720 and the patientspecific interior piece 2710 can be a single piece that is eitherpatient specific (where manufacturing costs of materials support such aproduct) or is reusable based on a library of substantially defectconforming shapes developed in response to known or common tibialsurface sizes and defects.

The interior piece 2710 is typically molded to the patella including thesubchondral bone and/or the cartilage.

From this determination, an understanding of the amount of space neededto optimally balance the knee is determined and an appropriate number ofspacers is then used in conjunction with the cutting block and mold toachieve the cutting surfaces and to prevent removal of too much bone.Where the cutting block has a thickness of, for example, 10 mm, and eachspacer has a thickness of 5 mm, in preparing the knee for cuts, two ofthe spacers would be removed when applying the cutting block to achievethe cutting planes identified as optimal during flexion and extension.Similar results can be achieved with ratchet or jack like designsinterposed between the mold and the cut guide.

vii. Hip Joint

Turning now to FIG. 18, a variety of views showing sample mold andcutting block systems for use in the hip joint are shown. FIG. 18 Aillustrates femur 2510 with a mold and cutting block system 2520 placedto provide a cutting plane 2530 across the femoral neck 2512 tofacilitate removal of the head 2514 of the femur and creation of asurface 2516 for the hip ball prosthesis.

FIG. 18 B illustrates a top view of the cutting block system 2520. Thecutting block system 2520 includes an interior, patient specific, moldedsection 2524 and an exterior cutting block surface 2522. The interior,patient specific, molded section 2524 can include a canal 2526 tofacilitate placing the interior section 2524 over the neck of the femur.As will be appreciated by those of skill in the art, the width of thecanal will vary depending upon the rigidity of the material used to makethe interior molded section. The exterior cutting block surface 2522 isconfigured to fit snugly around the interior section. Additionalstructures can be provided, similar to those described above withrespect to the knee cutting block system, that control movement of theexterior cutting block 2524 relative to interior mold section 2522, aswill be appreciated by those of skill in the art. Where the interiorsection 2524 encompasses all or part of the femoral neck, the cuttingblock system can be configured such that it aids in removal of thefemoral head once the cut has been made by, for example, providing ahandle 2501.

FIG. 18 C illustrates a second cutting block system 2550 that can beplaced over the cut femur to provide a guide for reaming after thefemoral head has been removed using the cutting block shown in FIG. 18A. FIG. 18 D is a top view of the cutting block shown in FIG. 18 C. Aswill be appreciated by those of skill in the art, the cutting blockshown in FIG. 18 C-18 D, can be one or more pieces. As shown in FIG. 18E, the aperture 2552 can be configured such that it enables the reamingfor the post of the implant to be at a 90° angle relative to the surfaceof femur. Alternatively, as shown in FIG. 18F, the aperture 2552 can beconfigured to provide an angle other than 90° for reaming, if desired.

FIGS. 19 A (sagittal view) and 19 B (frontal view, down onto mold)illustrates a mold system 2955 for the acetabulum 2957. The mold canhave grooves 2959 that stabilize it against the acetabular rim 2960.Surgical instruments, e.g. reamers, can be passed through an opening inthe mold 2956. The side wall of the opening 2962 can guide the directionof the reamer or other surgical instruments. Metal sleeves 2964 can beinserted into the side wall 2962 thereby protecting the side wall of themold from damage. The metal sleeves 2964 can have lips 2966 oroverhanging edges that secure the sleeve against the mold and help avoidmovement of the sleeve against the articular surface.

FIG. 19 C is a frontal view of the same mold system shown in FIGS. 19 Aand 19 B. A groove 2970 has been added at the 6 and 12 o'clockpositions. The groove can be used for accurate positioning or placementof surgical instruments. Moreover, the groove can be useful for accurateplacement of the acetabular component without rotational error. Someoneskilled in the art will recognize that more than one groove or internalguide can be used in order to not only reduce rotational error but alsoerror related to tilting of the implant. As seen FIG. 19 D, the implant2975 can have little extensions 2977 matching the grooves therebyguiding the implant placement. The extensions 2977 can be a permanentpart of the implant design or they can be detachable. Note metal rim2979 and inner polyethylene cup 2980 of the acetabular component.

FIG. 19 D illustrates a cross-section of a system where the interiorsurface 2960 of the molded section 2924 has teeth 2962 or grooves tofacilitate grasping the neck of the femur.

Various steps may be performed in order to design and make 3D guidancetemplates for hip implants, in accordance with an embodiment.

For example, in an initial step, a discrepancy in the length of the leftleg and right leg may be determined, for example, in millimeters. Leglength discrepancy may be determined, for example, using standingx-rays, typically including the entire leg but also cross-sectionalimaging modalities such as CT or MRI.

A CT scout scan may be utilized to estimate leg length. Alternatively,select image slices through the hip and ankle joint may be utilized toestimate leg length either using CT or MRI.

Pre-operative planning is then performed using the image data. A first3D guidance template is designed to rest on the femoral neck. FIG. 33shows an example of an intended site 4300 for placement of a femoralneck mold for total hip arthroplasty. A cut or saw plane integrated intothis template can be derived. The position, shape and orientation of the3D guidance mold or jig or template may be determined on the basis ofanatomical axis such as the femoral neck axis, the biomechanical axisand/or also any underlying leg length discrepancy (FIG. 29).Specifically, the superoinferior cut or saw guide height can be adaptedto account for leg length discrepancy. For example, if the left leg isfive (5) millimeters shorter than the right leg, then the cut height canbe moved by five (5) millimeters to account for this difference. Thefemoral neck cut height ultimately determines the position of thefemoral stem. Thus, in this manner, using this type of pre-operativeplanning, the femoral neck cut height can be optimized using a 3Dguidance template.

FIG. 29 is a flow diagram of a method wherein measurement of leg lengthdiscrepancy can be utilized to determine the optimal cut height of thefemoral neck cut for total hip arthroplasty. Initially, imaging isperformed, e.g. CT and/or MRI, through, without limitation, the hip,knee and ankle joint. Leg length discrepancy is determined, using theimaging data obtained. The desired implant size may then be optionallydetermined. The femoral neck cut position can be determined based, atleast in part, on correcting the leg length discrepancy for optimalfemoral component placement.

FIG. 34 shows another example of a femoral neck mold 4400 with handle4410 and optional slot 4420.

Acetabulum:

In the acetabulum, the position and orientation of the acetabularcomponent or acetabular cup is also critical for the success of hipsurgery. For example, the lowest portion of the acetabular cup may beplaced so that it is five (5) millimeters lateral to an anatomiclandmark on a pelvic x-ray coinciding with the inferior border of theradiographic tear drop. If the acetabular component is, for example,placed too far superiorly, significant bone may be lost.

Placing the acetabular component using the 3D guidance template mayinclude, for example, the following steps:

Step One: Imaging, e.g. using optical imaging methods, CT or MRI.

Step Two: Determining the anterior rotation of the acetabulum and thedesired rotation of the acetabular cup.

Step Three: Find best fitting cup size.

Step Four: Determine optimal shape, orientation and/or position of 3Dguidance template.

The template may be optionally designed to rest primarily on the marginof the acetabular fossa. In this manner, it is possible to ream throughthe template.

FIG. 35 shows an example of a posterior acetabular approach for totalhip replacement. Tissue retractors 4510 are in place. The acetabularfossa is visible 4520.

FIG. 36 shows an example of a guidance mold used for reaming the sitefor an acetabular cup. The mold 4600 can be optionally attached to ageneric frame 4610. A guide for the reamer is shown 4620. The reamer4630 or the mold can have optional stops 4640. In this example, thestops 4640 are attached to the reamer 4630 and engage the guide 4620 forthe reamer.

For purposes of reaming, the template may be fixed to the pelvis, forexample, using metal spikes or K-wires. The template may also have agrip for fixing it to the bone. Thus, a surgeon may optionally press thetemplate against the bone while a second surgeon will perform thereaming through the opening in the template. The grip or any stabilizerscan extend laterally, and optionally serve as tissue retractors, keepingany potentially interfering soft tissue out of the surgical field. Thetemplate may also include stoppers 4640 to avoid over penetration of thereamer. These stoppers may be designed in the form of metal stopsdefining the deepest penetration area for the peripheral portion orother portions of the reamer. Optionally, the template may also taperand decrease in inner radius thereby creating a stop once the reameronce the reaches the innermost portion of the template. Any stop knownin the art can be used. The imaging test can be used to design or shapethe mold in a manner that will help achieve the optimal reaming depth.The stops can be placed on the mold or reamer in reference to theimaging test in order to achieve the optional reaming depth.

A 3D guidance template may be utilized to optimize the anteversion ofthe acetabular cup. For example, with the posteral lateral approach,typically an anteversion of forty to forty-five degrees is desired inboth males and females. With an anterolateral approach, zero degreesanteversion may be desired. Irrespective of the desired degree ofanti-version, the shape, orientation and/or position of the template maybe optimized to include the desired degree of anteversion.

Similarly, on the femoral side, the 3D guidance template may beoptimized with regard to its shape, orientation and position in order toaccount for neutral, varus or valgus position of the femoral shaft. A 3Dguidance template may also be utilized to optimize femoral shaftanteversion.

Thus, after a first template has been utilized for performing thefemoral neck cut and a second template has been utilized for performingthe surgical intervention on the acetabular side, a third template mayoptionally be utilized to be placed onto the femoral cut.

Optionally, modular hip implant components may be utilized such as amodular stem. Such modular designs can be helpful in further optimizingthe resultant femoral anteversion by selecting, for example, differentstem shapes.

In another embodiment, the surgeon may perform a femur first techniquewherein a first cut is applied to the femur using a first 3D guidancemold. Optionally, the broach in the cut femoral shaft may be left inplace. Optionally, a trial implant head may be applied to the broach.The trial implant head may be variable in radius and superoinferiordiameter and may be utilized to determine the optimal soft tissuetension. Optionally, the trial head may also be utilized to determinethe acetabular cup position wherein said acetabular cup position isderived on the basis of the femoral cut. Thus, the acetabular positioncan be optionally derived using the opposite articular surface. In areverse acetabulum first technique, the acetabulum can be prepared firstand, using soft tissue balancing techniques, the femoral component canbe placed in reference to the acetabular component. Optionally, thefemoral cut may even be placed intentionally too proximal and issubsequently optimized by measuring soft tissue tension utilizingvarious trial heads with the option to then change the height of theoptimal femoral cut.

viii. Positioning of Template

In an illustrative embodiment, in order to make a guidance templatereliably and reproducibly, a portion of the joint is identified in afirst step wherein said portion of the joint has not been altered by thearthritic process. In a second step, the surface or a point cloud ofsaid portion of the joint is derived, and may, optionally, be used toderive a virtual 3D model and, in a third step, to generate a physicalmodel as part of the guidance template. Using a portion of the jointthat has not been altered by the arthritic process can advantageouslyimprove the reproducibility and the accuracy of the resultant mold orjig or template.

The step of identifying said portion of the joint may be visual,semiautomatic or fully automatic. Anatomic models may assist in theprocess. Anatomic reference standards may be utilized.

As known in the art, various methods for image segmentation may be usedto derive the point cloud or the surface. Suitable algorithms include,for example, but are not limited to snakes, live wire, thresholding,active contours, deformable models and the like. Artificial neuralnetworks may be employed to improve the accuracy of the molds.

In another embodiment, the current biomechanical axis may determined orestimated in a first step. In a second step, the desired biomechanicalaxis is determined. In a third step adjustments, for example via changein slot position or position for openings for saws and drills and thelike, may be made to alter the cut or drill position in order to correctthe biomechanical axis in a fourth step. In a fifth step, the positionof the slot or openings for saws and drills and the like may be adjustedfor ligament balancing and/or for optimizing flexion and extension gap.This adjustment may be performed in the 3D model prior to themanufacturing process. Alternatively, adjustments may be madeintraoperatively, for example via spacers or ratchet like devices orpins to allow for some degree of rotation.

In another embodiment, at least a portion of the surface of the mold orjig or template is derived from a portion of the joint that is affectedby the arthritic process. Optionally, adjustment means can be performed,for example via the software, to simulate a normal shape. The differencebetween the actual shape and the adjusted shape can be utilized tooptimize the position of the slots or openings in the mold or templateor jig.

In one embodiment, at least a portion of the surface of the mold or jigor template that is in contact with the joint may be derived from aportion of the joint that is affected by the arthritic process and aportion of the joint that has not been altered by the arthritic process.By spanning both normal and diseased portions of the joint, theinterface between normal and diseased portions of the joint is includedin the surface of the mold. The interface between normal and diseasedportions of the joint is typically characterized by a sudden change incontour or shape, e.g. a reduction in cartilage thickness, a change insubchondral bone contour, a cyst or a bone spur. This change in jointcontour or shape provides additional reference points for accuratelyplacing the mold or jig or template. In addition, this change in jointcontour or shape provides also additional stabilization or fixation ofthe mold or jig or template on the surface of the joint, in particularwhile performing surgical interventions such as cutting, drilling orsawing.

ix. Anatomical Relief

In deriving and manufacturing various embodiments, it may beadvantageous to provide one or more anatomical relief surfaces orportions (of varying degrees) to the surgical tools and/or implantsdisclosed herein.

Where an implant or surgical tool incorporates a surface thatsubstantially matches or conforms to one or more anatomical structures,it may be desirable to avoid or specifically preclude certain areas ofthe matching/conforming surface from contacting and/orconforming/matching to the underlying anatomy by offsetting, subtractingor otherwise modifying sections of the surface portions adjacent to suchareas. Specific instances where such anatomical relief could beparticularly advantageous can include, but are not limited to,anatomical areas that are difficult to access; difficult to denude,clean, debride or otherwise prepare; areas that are incompatible withminimal access procedures and/or other areas that are desirable to avoidfor other surgical reasons.

Anatomical relief can be achieved during the construction ormodification of the surface prior to any rapid prototyping or CNC orother manufacturing method of an instrument or an implant withpatient-adapted or patient-specific features. Anatomic relief can alsobe achieved after manufacturing of such components for example bysubtraction of physical material, e.g. through some grinding, CNC,polishing, heat, air or laser abrasion or other methods known in the artor developed in the future for removing material. Similarly, anatomicalrelief may be accomplished by additive manufacturing process that “buildup” or otherwise alter conforming surfaces to the joint.

Anatomical relief surfaces can form part of (or be encompassed by) theconforming surface, such that a perimeter of the anatomical reliefsurface is completely surrounded by the conforming surface. In otherembodiments, the anatomical relief surface may be partially surroundedby the conforming surface. In still other embodiments, the anatomicalrelief surface may by separated from the conforming surface, such aswhere the anatomical relief surface is on the periphery of the tool orimplant, and/or on the “joint facing, “externally facing” and/orarticulating surfaces of the tool or implant.

FIGS. 37 through 41 depict one embodiment of a procedure forincorporating and/or designing an anatomical relief into a surgicaltool. In this embodiment, a two or three-dimensional computer model ofan intended surgical site (a femur, in this example) is referenced, andan inner surface 5100 (including, for example, a trochlear groove) isselected. An offset surface 5110 (see FIG. 38) can then be derived fromthe inner surface 5100. In one embodiment, the offset surface 5110 canbe derived by sampling a plurality of discrete points or pixels/voxelsof the inner surface 5100, and displacing the points from inner surface5100 a set amount, such as 0.1 mm, 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, 2 mmor any desired spacing and/or in any direction (generally perpendicularin this example or at an angle other than 90 degrees), therebyconstructing the offset surface. If desired, the creation of the offsetsurface 5110 may duplicate the underlying anatomy, or it may furtherinclude a filtering or planarizing function which desirably smooths orotherwise modifies the offset surface to some degree relative to theinner surface. Depending upon the type and/or features of the innersurface, as well as the location of the anatomy, varying spacings,displacements and/or directions may be utilized, with varying results(i.e., the offset may be constant for the entire surface, or may vary indifferent locations along the surface.

Once the offset surface 5110 has been derived, the inner surface 5100and/or anatomical model can be removed and/or hidden, and a surgicaltool 5120 can be overlaid onto the offset surface 5110, as best seen inFIG. 39. One or more relevant portions of the surgical tool 5120 arethen merged onto the offset surface 5110, as shown in FIG. 40. Once thesurgical tool has been merged and modeled, the model can be utilized tomanufacture the surgical tool incorporating the desired anatomicalrelief 5130 (or can be used to modify a pre-existing tool or implant).In the embodiment shown in FIG. 41, the surgical tool incorporates ananatomical relief or clearance zone that corresponds to a regionadjacent to the trochlear groove of the femur, which desirably reducesor obviates the need for complete removal of all structures and/or softtissues (e.g., cartilage and/or osteophytes) within the groove anddirectly surrounding areas.

Derivation and use of the offset surface in this manner desirablyprovides substantially conforming and/or matching surfaces for alignmentand placement of surgical tools and implants, but allowing clearance forareas of anatomical concern and/or avoidance. In addition, maintaining adesired minimal clearance allows avoidance of specific anatomy while,for example, optionally maintaining a minimal thickness of the toolmaterial to ensure tool integrity. The disclosed procedure also providesa repeatable and easily identifiable method of identifying a region ofinterest and quickly and easily constructing an appropriate anatomicalrelief structure to accommodate some or all of the region.

FIGS. 42 through 45 depict an alternative embodiment of a procedure forincorporating an anatomical relief into a surgical tool. In thisexample, a two or three-dimensional computer model of an intendedsurgical site (a femur, in this example) is referenced, and a trochleargroove sketch 5200 is derived by creating a sagittal silhouette sketchof the central trochlea, for example, at its most proximal point (FIGS.42 and 43) or its central or its most distal point. If desired, thetrochlear groove sketch may follow the natural contour(s) of thetrochlear groove, or may comprise an actual or stylized two-dimensionalrepresentation of the three dimensional trochlear groove as projected ona plane passing through the femur at a desired angle and/or inclinationrelative to the groove. The same applies to any other anatomic site,e.g. a glenoid including the center of a glenoid or an acetabular fossa.In this example, the trochlear groove sketch 5200 is then laterallyexpanded 5205 (i.e., along one or more medial/lateral or otherdirection(s)) and then overlaid onto a relevant region of a surgicaltool 5210 (see FIG. 44). One or more relevant portions of the surgicaltool 5210 is then merged onto the laterally expanded sketch 5205, asshown in FIG. 44, which in effect “subtracts” or removes a portion ofthe substantially conforming and/or matching surface in one or moreregions of interest. Once the surgical tool has been merged and modeled,the model can be utilized to manufacture the surgical tool incorporatingthe desired anatomical relief 5230. In the embodiment shown in FIG. 45,the surgical tool incorporates an anatomical relief or clearance zone5230 that corresponds to a region adjacent to the trochlear groove ofthe femur, which desirably reduces or obviates the need for completeremoval of all structures and/or soft tissues (e.g., cartilage and/orosteophytes) within the groove and/or surrounding anatomical regions.Moreover, the anatomical relief obviates, to some degree, the need tomeasure and duplicate the exact anatomy of the entirety of the trochleargroove, while still providing for accurate tool placement using theremaining conforming and/or matching surfaces to align the tool in adesired manner.

In another embodiment, an anatomic relief can be achieved by notincluding or excluding select regions of anatomy from an imagesegmentation or 2D or 3D rendering or reconstruction of a surface.

In another embodiment, an anatomic relief can be obtained by editing oneor more contours on the original, native images, e.g. CT, MRI orultrasound, for example, by moving an articular surface in a desireddirection to achieve or simulate the anatomic relief.

In a further embodiment, shown in FIG. 51 B, a cross-sectional view of asurgical tool 5266 depicts a “sawtooth” pattern reference surface havingmultiple anatomical relief surfaces 5267. The tool incorporates aplurality of reference surfaces 5268 that can be designed to contactand/or substantially conform to portions of the natural anatomy of thetrochlear groove 5200. The reference surfaces 5268 can be designedand/or selected to contact the natural articular surface(s), damagedarticular surface(s) and/or subchondral bone surface(s) (either or withor without articular cartilage removed), or combinations thereof.

FIGS. 46 through 51 A depict additional alternative embodiments ofsurgical tools incorporating anatomical reliefs. The surgical tools ofthese embodiments desirably include one or more portions of thelaterally expanded trochlear groove sketch 5205 of FIG. 44, and thesetools desirably comprise additional components for use in implanting apartial or total joint knee joint replacement. The tools of FIGS. 42through 51 A, and the derivations and constructions thereof, would beespecially well suited for use with the total knee implants and surgicaltools described in U.S. Provisional Patent Application No. 61/443,155 toBojarski et al, filed Feb. 15, 2011, and entitled “Patient-Adapted andImproved Articular Implants, Designs and Related Guide Tools,” thedisclosure of which is incorporated by reference herein. FIGS. 46 and 47depict an alignment jig 5240 with an anatomical relief or clearance zone5245 that corresponds to a region adjacent to the trochlear groove ofthe femur. FIGS. 48 and 49 depict an alignment jig 5250 with ananatomical relief or clearance zone 5255 that corresponds to a regionadjacent to the trochlear groove of the femur. FIGS. 50 and 51 A depictan alignment jig 5260 with an anatomical relief or clearance zone 5265that corresponds to a region adjacent to the trochlear groove of thefemur.

It should be understood that such anatomical reliefs may be utilized toaccommodate anatomical variations in all joints, including those of theknee, shoulder, hip, vertebrae, elbow, ankle, wrist, etc. In addition,the anatomical relief surfaces described herein would have equal utilityfor incorporation into various implants, including partial or totaljoint replacement implants, as well as surgical tools and/or molds.

VI. Kits

Also described herein are kits comprising one or more of the methods,systems and/or compositions described herein. In particular, a kit caninclude one or more of the following: instructions (methods) ofobtaining electronic images; systems or instructions for evaluatingelectronic images; one or more computer means capable of analyzing orprocessing the electronic images; and/or one or more surgical tools forimplanting an articular repair system. The kits can include othermaterials, for example, instructions, reagents, containers and/orimaging aids (e.g., films, holders, digitizers, etc.).

The following examples are included to more fully illustrate the variousdisclosures herein. Additionally, these examples describe variousspecific embodiments, they are not meant to limit the scope thereof ofthe systems and methods described herein.

Example 1 Design and Construction of a Three-Dimensional ArticularRepair System

Areas of cartilage are imaged as described herein to detect areas ofcartilage loss and/or diseased cartilage. The margins and shape of thecartilage and subchondral bone adjacent to the diseased areas aredetermined. The thickness of the cartilage is determined. The size ofthe articular repair system is determined based on the abovemeasurements. In particular, the repair system is either selected (basedon best fit) from a catalogue of existing, pre-made implants with arange of different sizes and curvatures or custom-designed using CAD/CAMtechnology. The library of existing shapes is typically on the order ofabout 30 sizes.

The implant is a chromium cobalt implant. The articular surface ispolished and the external dimensions slightly greater than the area ofdiseased cartilage. The shape is adapted to achieve perfect or nearperfect joint congruity utilizing shape information of surroundingcartilage and underlying subchondral bone. Other design features of theimplant can include: a slanted (60- to 70-degree angle) interface toadjacent cartilage; a broad-based base component for depth control; apress fit design of base component; a porous coating of base componentfor ingrowth of bone and rigid stabilization; a dual peg design forlarge defects implant stabilization, also porous coated; a singlestabilizer strut with tapered, four fin and step design for small, focaldefects, also porous coated; and a design applicable to femoralresurfacing (convex external surface) and tibial resurfacing (concaveexternal surface).

Example 2 Minimally Invasive, Arthroscopically Assisted SurgicalTechnique

The articular repair systems are inserted using arthroscopic assistance.The device does not require the 15 to 30 cm incision utilized inunicompartmental and total knee arthroplasties. The procedure isperformed under regional anesthesia, typically epidural anesthesia. Thesurgeon can apply a tourniquet on the upper thigh of the patient torestrict the blood flow to the knee during the procedure. The leg isprepped and draped in sterile technique. A stylette is used to createtwo small 2 mm ports at the anteromedial and the anterolateral aspect ofthe joint using classical arthroscopic technique. The arthroscope isinserted via the lateral port. The arthroscopic instruments are insertedvia the medial port. The cartilage defect is visualized using thearthroscope. A cartilage defect locator device is placed inside thediseased cartilage. The probe has a U-shape, with the first arm touchingthe center of the area of diseased cartilage inside the joint and thesecond arm of the U remaining outside the joint. The second arm of the Uindicates the position of the cartilage relative to the skin. Thesurgeon marks the position of the cartilage defect on the skin. A 3 cmincision is created over the defect. Tissue retractors are inserted andthe defect is visualized.

A translucent Lucite block matching the 3D shape of the adjacentcartilage and the cartilage defect is placed over the cartilage defect.For larger defects, the Lucite block includes a lateral slot forinsertion of a saw. The saw is inserted and a straight cut is madeacross the articular surface, removing an area slightly larger than thediseased cartilage. The center of the Lucite block contains two drillholes with a 7.2 mm diameter. A 7.1 mm drill with drill guidecontrolling the depth of tissue penetration is inserted via the drillhole. Holes for the cylindrical pegs of the implant are created. Thedrill and the Lucite block are subsequently removed.

A plastic model/trial implant of the mini-repair system matching theouter dimensions of the implant is then inserted. The trial implant isutilized to confirm anatomic placement of the actual implant. Ifindicated, the surgeon can make smaller adjustments at this point toimprove the match, e.g. slight expansion of the drill holes oradjustment of the cut plane.

The implant is then inserted with the pegs pointing into the drillholes. Anterior and posterior positions of the implant are color-coded;specifically the anterior peg is marked with a red color and a smallletter “A”, while the posterior peg has a green color and a small letter“P”. Similarly, the medial aspect of the implant is color-coded yellowand marked with a small letter “M” and the lateral aspect of the implantis marked with a small letter “L”. The Lucite block is then placed onthe external surface of the implant and a plastic hammer is used togently advance the pegs into the drill holes. The pegs are designed toachieve a press fit.

The same technique can be applied in the tibia. The implant has aconcave articular surface matching the 3D shape of the tibial plateau.Immediate stabilization of the device can be achieved by combining itwith bone cement if desired.

Example 3 Design and Construction of a Implant and/or Surgical ToolIncorporating a Negative Anatomical Relief

Anatomical relief features can be used to accommodate or otherwiseaddress osteophytes, subchondral voids, residual normal or diseasedcartilage or combinations thereof and other patient-specific defects orabnormalities. In the case of osteophytes, the osteophyte can beintegrated into the shape of the bone or joint facing surface of theimplant component or guide tool. FIGS. 52A and 52B are exemplarydrawings of an end of a femur 1010 having an osteophyte 1020. In theselection and/or design of an implant component for a particularpatient, an image or model of the patient's bone that includes theosteophyte or other surface feature can be utilized as a model forcreating, designing and/or selecting an implant and/or surgical toolhaving one or more conforming surfaces. If desired, the portion of theimage having the surface feature may be modified, transformed,cross-referenced, smoothed and/or enhanced, which could be utilized toincrease the imaging accuracy of the osteophyte and/or account forinaccuracies or potential inaccuracies in detection and/or modeling ofthe osteophyte's surface. In one embodiment, as shown in FIG. 52B, animplant (or surgical tool) component 1050 can be selected and/ordesigned to include a negative anatomical relief conforming to the shapeof the osteophyte 1020. In alternative embodiments, the anatomicalrelief could be sized and/or configured to accommodate more than theosteophyte (i.e., the anatomical relief cavity could be larger than theosteophyte, or could be shaped differently or “filtered” to accommodatemore than the osteophyte). In certain embodiments, the anatomical reliefmay contact part, but not all, of the osteophyte or other anatomicalstructure (i.e., the anatomical relief may be oversized to encompass theentirety of the osteophyte, with optionally some portion of theosteophyte touching a wall of the anatomical relief). In otherembodiments, the anatomical relief may encompass only a portion of theosteophyte or other anatomical structure, such as where a portion of theanatomical structure lies within the anatomical relief and otherportions of the anatomical structure extend outside of the anatomicalrelief.

As another example, a tibial component can be designed either before orafter virtual modification of various features of the tibial bone,including surface features, have been accomplished. In one embodiment,the initial design and placement of the tibial tray and associatedcomponents can be planned and accomplished utilizing informationdirectly taken from the patient's natural anatomy. In various otherembodiments, the design and placement of the tibial components can beplanned and accomplished after virtual modification of various boneportions, including the removal, modification and/or enhancement of oneor more cut planes (to accommodate the tibial implant) as well as thevirtual removal, modification and/or enhancement of variouspotentially-interfering structures (i.e., overhanging osteophytes,etc.). Someone skilled in the art will readily recognize that this isreadily achievable also with a procedure that is based on burring. Priorvirtual removal, modification, enhancement and/or filling of suchstructures can facilitate and improve the design, planning and placementof tibial components, and prevent anatomic distortion from significantlyaffecting the final design and placement of the tibial components. Forexample, once one or more tibial cut planes has been virtually removedor once an implant bed has been designed for a burring procedureincluding a robotic procedure, the size, shape and rotation angle of atibial implant component can be more accurately determined from thevirtually cut surface, as compared to determining the size, shape and/ortibial rotation angle of an implant from the natural tibial anatomyprior to such cuts. In a similar manner, structures such as overhangingosteophytes can be virtually removed (either alone or in addition tovirtual removal of the tibial cut plane(s)), modified (such as, forexample, by incorporating a cut plane in the osteophyte that forms anaddition or extension to an existing cut plane on the bone) with thetibial implant structure and placement (i.e., tibial implant size, shapeand/or tibial rotation, etc.) subsequently planned. Of course, virtuallyany unusual and/or undesirable anatomical features or deformity,including (but not limited to) altered bone axes, flattening, potholes,cysts, scar tissue, osteophytes, tumors and/or bone spurs may besimilarly virtually removed, modified, modeled and/or otherwise utilizedin the implant and/or surgical tool design and placement.

Example 4 Design and Construction of a Implant and/or Surgical ToolIncorporating a Positive Anatomical Relief

Similarly, to address a subchondral void, a selection and/or design forthe bone-facing surface of an implant component can include a positiveanatomical relief integrated into the shape of the bone-facing surfaceof the implant component. FIGS. 53A and 53B are exemplary drawings of anend of a femur 1110 having a subchondral void 1120. During developmentof an implant, an image or model of the patient's bone that includes thevoid can be utilized in creating, designing and/or selecting an implantand/or surgical tool surface that conforms to the shape of void 1120, asshown in FIG. 53B. In various other embodiments, the image may bevirtually altered to include additional removal, filling, modification,filtering, smoothing and/or enhancement of voids, etc., includingvirtual removal of the void, if desired. Moreover, it may be desirousthat the positive anatomical relief does not completely conform to thevoid 1120, such as where the implant 1150 might not practically be ableto be inserted into the void. Therefore, in certain embodiments, theimplant and/or surgical tool may only partially protrude into a void inthe bone. Optionally, a surgical strategy and/or one or more guide toolscan be selected and/or designed to reflect the correction and correspondto the implant component.

In addition to osteophytes and subchondral voids, the methods, surgicalstrategies, guide tools, and implant components described herein can beused to address various other patient-specific joint defects orphenomena. In certain embodiments, correction can include the virtualremoval of tissue, for example, to address an articular defect, toremove subchondral cysts, and/or to remove diseased or damaged tissue(e.g., cartilage, bone, or other types of tissue), such asosteochondritic tissue, necrotic tissue, and/or torn tissue. In suchembodiments, the correction can include the virtual removal or othermodification of the tissue image data (e.g., the tissue corresponding tothe defect, cyst, disease, or damage) and the bone-facing surface of theimplant component can be derived after the tissue has been virtuallyremoved or modified. For example, if bone is several eburnated, it isfeasible to add material to the bone virtually and then form or designan implant. In certain embodiments, the implant and/or surgical toolcomponent can be selected and/or designed to include a thickness orother anatomical features that substantially matches the positive and/ornegative (or various combinations thereof) of the surface features,including any virtually removed or added tissues. Alternatively, themodification can include optimizing additional functional or one or moreother parameters of the joint. Optionally, a surgical strategy and/orone or more guide tools can be selected and/or designed to reflect thecorrection and correspond to the implant component

Example 5 Design and Construction of a Surgical Tool IncorporatingMultiple Anatomical Reliefs

In certain embodiments, one or more additional models or sets of modelsof the patient's biological structure also can be generated and conveyedto the surgeon or clinician to show an additional presence, or absence,of one or more defects of interest, one or more resection cuts, one ormore guide tools, and/or one or more implant components, or anycombination of these. FIGS. 54A through 54D and 55A through 55Dillustrate models for one particular patient receiving a singlecompartment knee implant having both femoral and tibial implantcomponents. FIGS. 54A and 54B depict two perspective views of apatient's distal femur, and FIGS. 54C and 54D depict two images of thepatient's proximal tibia, with patient-adapted guide tools shown inFIGS. 54B and 54D. In these figures, anatomical defects or other surfacestructures, which are osteophytes in this example, are categorized anddifferentiated into two shades, lighter and darker. The lighter-coloredosteophytes 1210 depict osteophytes that do not interfere with placementof a surgical guide tool or implant components. The darker-shadedosteophytes 1220 depict osteophytes that are anticipated to interferewith placement of a surgical guide tool or implant component.Accordingly, this embodiment includes the categorization of theosteophytes or other surface features to serve as a guide or referenceto the surgeon or clinician in determining which, if any, osteophytesshould be removed prior to placement of the guide tools or implantcomponents and/or which, if any, osteophytes should be accommodatedusing, for example, an anatomical relief, during placement of either orboth of the surgical guide tool (or tools) or implant components

FIGS. 55A and 55B depict two images, respectively, of a patient's distalfemur with a patient-adapted guide tool and with a patient-adaptedunicompartmental femoral implant component. FIGS. 55C and 55D depict twoimages, respectively, of the patient's proximal tibia, with apatient-adapted guide tool and with a patient-adapted unicompartmentaltibial implant component. While the images in this figure show noosteophytes, it should be understood that in various embodiments suchosteophytes could have been surgically removed, while in otherembodiments, the osteophytes could remain and be accommodated using, forexample, anatomical reliefs on the various surgical tools and/orimplants. In a similar manner, various other embodiments could includetools and/or implants that include anatomical reliefs to accommodatesome surface features (i.e., osteophytes, etc.), while other surfacefeatures are surgically removed.

FIGS. 55C and 55D further depict a further embodiment where the surgicaltool of FIG. 55C incorporates an anatomical relief (not shown) while thecorresponding implant FIG. 55D does not include an anatomical reliefsurface. The surgical tool, which serves as an alignment guide forcreation of a cutting plane, uses the anatomical surface of the tibia(including surface features such as osteophytes, etc.), which, in thisembodiment, optionally mandates the inclusion of one or more anatomicalrelief surfaces to accommodate these surface features. The implant,however, rests completely upon the surgically cut plane, and thus neednot include an anatomical relief, as desired, for proper placement andfixation on the cut tibial surface.

FIGS. 56A through 56D and 57A through 57D illustrate models for adifferent patient receiving a bicompartmental knee implant having bothfemoral and tibial implant components. The features in FIGS. 56A through56D and 57A through 57D are similar to those described above for FIGS.54A through 54D and 55A through 55D. In comparing the models for the twodifferent individuals, the individual receiving the unicompartmentalknee implant possesses substantially more osteophyte coverage than theindividual receiving the bicompartmental knee implant.

Example 6 Identification, Classification and/or Modification of RelevantSurface Defects and/or Other Anatomical Features Relevant to thePotential Inclusion of Anatomical Relief Surfaces

In certain embodiments, the reference points and/or anatomical featuresof a patient can be can be processed using mathematical functions toderive virtual, corrected features, which may represent a restored,ideal or desired feature from which a patient-adapted implant componentcan be designed. For example, one or more features, such as surfaces ordimensions of a biological structure can be modeled, altered, added to,changed, deformed, eliminated, corrected and/or otherwise manipulated(collectively referred to herein as “variation” of an existing surfaceor structure within the joint). While it is described in the knee, theseembodiments can be applied to any joint or joint surface in the body,e.g. a knee, hip, ankle, foot, toe, shoulder, elbow, wrist, hand, and aspine or spinal joints.

Variation of the joint or portions of the joint can include, withoutlimitation, variation of one or more external surfaces, internalsurfaces, joint-facing surfaces, uncut surfaces, cut surfaces, alteredsurfaces, and/or partial surfaces as well as surface/subsurface and/orexternal features such as osteophytes, subchondral cysts, geodes orareas of eburnation, joint flattening, contour irregularity, and loss ofnormal shape. The surface or structure can be or reflect any surface orstructure in the joint, including, without limitation, bone surfaces,ridges, plateaus, cartilage surfaces, ligament surfaces, or othersurfaces or structures. The surface or structure derived can be anapproximation of a healthy joint surface or structure or can be anothervariation. The surface or structure can be made to include pathologicalalterations of the joint. The surface or structure also can be madewhereby the pathological joint changes are virtually removed in whole orin part.

Computer software programs to generate models of patient-specificrenderings of implant assembly and defects (e.g., osteophyte or otheranatomical structures), together with bone models, to aid in surgeryplanning can be developed using various publicly available programmingenvironments and languages, for example, Matlab 7.3 and Matlab Compiler4.5, C++ or Java. In certain embodiments, the computer software programcan have a user interface that includes one or more of the componentsidentified in FIG. 58. Alternatively, one or more off-the-shelfapplications can be used to generate the models, such as SolidWorks,Rhinoceros, 3D Slicer or Amira.

An illustrative flow chart of the high level processes of an exemplarycomputer software program is shown in FIG. 59. Briefly, a data pathassociated with one or more patient folders that include data files, forexample, patient-specific CT images, solid models, and segmentationimages, is selected. The data files associated with the data path can bechecked, for example, using file filters, to confirm that all data filesare present. For example, in generating models for a knee implant, adata path can confirm the presence of one, several, or all coronal CT orMRI data files, sagittal CT or MRI data files, a femoral solid modeldata file, a tibial solid model data file, a femoral guide tool model, atibial guide tool model, a femoral coronal segmentation model, a femoralsagittal segmentation model, a tibial coronal segmentation model, and atibial sagittal segmentation model. If the filter check identifies amissing file, the user can be notified. In certain instances, forexample, if a tibial or femoral guide tool model file is unavailable,the user may elect to continue the process without certain steps, forexample, without guide tool—defect (e.g., osteophyte or other surfacefeature) interference analysis.

Next, a patient-specific cartilage or bone-surface model is obtainedand/or rendered. The cartilage or bone surface model provides basicpatient-specific features of the patient's biological structure andserves as a reference for comparison against a model or value thatincludes the defect(s) and/or surface features of interest. As anillustrative example, previously generated patient-specific files, forexample, STL files exported from “SOLID” IGES files in SolidWorks, canbe loaded, for example, as triangulation points with sequence indicesand normal vectors. The triangles then can be rendered (e.g., usingMatlab TRISURF function) to supply or generate the cartilage orbone-surface model. The cartilage or bone surface model can includedefects and/or other surface features, such as osteophytes. If desired,some or all of these surface features may selectively be analyzed,assessed, corrected, filtered, removed, filled, smoothed, modified inshape or size or composition, enhanced or otherwise manipulated and/orcross-referenced with other features in the same image or with similarfeatures from other images. In this fashion, one or more cartilageand/or bone models, implant models and/or surgical tool models can beobtained and/or rendered.

Next, a patient-specific model or values of the patient's biologicalfeature that include the defect of interest (or other surface features)can be obtained, rendered and/or otherwise manipulated. For example,patient-specific surface features such as osteophytes can be identifiedfrom analysis of the patient's segmentation images and corresponding CTscan images. The transformation matrix of scanner coordinate space toimage matrix space can be calculated from image slice positions (e.g.,the first and last image slice positions). Then, patient-specificsegmentation images for the corresponding scan direction can beassessed, along with CT image slices that correspond to the loadedsegmentation images. Images can be processed slice by slice or as avolume and, using selected threshold values (e.g., intensity thresholds,Hounsfield unit thresholds, or neighboring pixel/voxel valuethresholds), pixels and/or voxels corresponding to the surface featureof interest (e.g., osteophytes) can be identified. The identified voxelscan provide a binary cartilage or bone surface volume that includes thesurface features of interest as part of the surface of the patient'sbiological structure. If desired, various masks can be employed to maskout surface features that are not of interest, for example, an adjacentbiological surface. In some instances, masking can generate apparentunattached portions of an osteophyte defect or other surface feature,for example, when a mask covers a portion of an osteophyte extension.

Next, the surface features of interest are isolated by comparing themodel that does not include the defects of interest (e.g., cartilage orbone-surface model) with the model or value that does include thesurface features of interest (e.g., the binary cartilage or bone surfacevolume). For example, the triangulation points of the cartilage or bonesurface model can be transformed onto an image volume space to obtain abinary representation of the model. This volume binary can be dilatedand thinned to obtain a binary cartilage or bone model. The binary bonemodel then can serve as a mask to the binary cartilage or bone surfacevolume to identify surface feature volume separate from the binarycartilage or bone surface volume. For example, for osteophyte detection,the osteophyte volume (e.g., osteophyte binary volume), as well as theosteophyte position and attachment surface area, can be distinguishedfrom the patient's biological structure using this comparative analysis.Various thresholds and filters can be applied to remove noise and/orenhance surface feature detection in this step. For example, structuresthat have less than a minimum voxel volume (e.g., less than 100 voxels)can be removed. Alternatively, or in addition, rules can be added to“reattach” any portion of an osteophyte or other surface feature thatappears unattached, e.g., due to a masking step.

In an alternative approach, surface data can be used instead of voxel orvolume data when comparing the bone surface model with corrected surfacefeatures and the patient's actual bone surface. The bone surface model,for example, can be loaded as a mesh surface (e.g. in an STL file) or aparametric surface (e.g. in an IGES file) without conversion tovolumetric voxel data. The patient's natural cartilage or bone surfacecan be derived from the medical image data (e.g. CT data) using, forexample, a marching cubes or isosurface algorithm, resulting in a secondsurface data set. The cartilage or bone surface model and the naturalcartilage or bone surface can be compared, for example, by calculatingintersection between the two surfaces.

In another alternative approach, the 3D representation of the biologicalstructure can be generated or manipulated, for example, smoothed orcorrected, for example, by employing a 3D polygon or mesh surface, asubdivision surface or parametric surface, for example, a non-uniformrational B-spline (NURBS) surface, or an implicit surface. For adescription of various parametric surface representations see, forexample Foley, J. D. et al., Computer Graphics Principles and Practicein C; Addison-Wesley, 2nd edition (1995). Various methods are availablefor creating a parametric surface. For example, the 3D representationcan be generated directly as a parametric surface from image data of thebiological structure, for example CT or MR images, by approximating thecontours of the biological structure with the surface. Alternatively, aparametric surface can be best-fit to the 3D representation byconnecting data points to create a surface of polygons and applyingrules for polygon curvatures, surface curvatures, and other features, orusing publicly available software such as Geomagic® software (ResearchTriangle Park, N.C.). Other possible 3D representations of thebiological structure can be defined as implicit surfaces, such as levelsets, isosurfaces, or adaptive data structures. Alternatively, thesurface can be represented volumetrically or as a point cloud.

Next, optionally, the models can be used to detect interference betweenany surface feature volume and the placement of one or more guide toolsand/or implant components. For example, guide tool model triangulationpoints can be transformed onto an image volume space to obtain a binaryrepresentation of the guide tool. The binary structure then can bemanipulated (e.g., dilated and eroded using voxel balls having pre-setdiameters) to obtain a solid field mask. The solid field mask can becompared against the surface feature volume, for example, the osteophytebinary volume, to identify interfering surface feature volume, forexample, interfering osteophyte binary volume. In this way, interferingsurface feature volume and non-interfering surface feature volume can bedetermined (e.g., using Matlab ISOSURFACE function), for example, usingrepresentative colors or some other distinguishing features in a model.The resulting model image can be rendered on a virtual rendering canvas(e.g., using Matlab GETFRAME function) and saved onto acomputer-readable medium.

Finally, optionally, as exemplified by FIGS. 54A through 57D, one ormore combinations of model features can be combined into one or modelsor sets of models that convey desired information to the surgeon orclinician. For example, patient-specific cartilage or bone models can becombined with any number of surface features and/or surface featuretypes, any number of resection cuts, any number of drill holes, anynumber of axes, any number of guide tools, and/or any number of implantcomponents to convey as much information as desired to the surgeon orclinician. The patient-specific cartilage or bone model can model anybiological structure, for example, any one or more (or portion of) afemoral head and/or an acetabulum; a distal femur, one or both femoralcondyle(s), and/or a tibial plateau; a trochlea and/or a patella; aglenoid and/or a humeral head; a talar dome and/or a tibial plafond; adistal humerus, a radial head, and/or an ulna; and a radius and/or ascaphoid. Surface features that can be combined with a patient-specificcartilage or bone model can include, for example, osteophytes, voids,subchondral cysts, articular shape defects (e.g., rounded or flattenedarticular surfaces or surface portions), varus or valgus deformities, orany other deformities or other surface or subsurface or external (i.e.,non-surface or subsurface) features known to those in the art.

The models can include virtual corrections and/or modificationsreflecting a surgical plan, such as one or more removed or modifiedsurface features such as osteophytes, cut planes, drill holes,realignments of mechanical or anatomical axes. The models can includecomparison views demonstrating the anatomical situation before and afterapplying the planned correction. The individual steps of the surgicalplan can also be illustrated in a series of step-by-step images whereineach image shows a different step of the surgical procedure.

The models can be presented to the surgeon as a printed or digital setof images. In another embodiment, the models are transmitted to thesurgeon as a digital file, which the surgeon can display on a localcomputer. The digital file can contain image renderings of the models.Alternatively, the models can be displayed in an animation or video. Themodels can also be presented as a 3D model that is interactivelyrendered on the surgeon's computer. The models can, for example, berotated to be viewed from different angles. Different components of themodels, such as cartilage or bone surfaces, surface features and/ordefects, resection cuts, axes, guide tools or implants, can be turned onand off collectively or individually to illustrate or simulate theindividual patient's surgical plan. The 3D model can be transmitted tothe surgeon in a variety of formats, for example in Adobe 3D PDF or as aSolidWorks eDrawing.

Example 7 The Use of External Anatomical Relief Surfaces to AccommodateNon-Joint Surfaces and/or Structures

Implant and or surgical tool selection, design and modeling can alsoincorporate external anatomical relief surfaces to facilitate surgicalprocedures and implants that are ligament sparing, as well as for othersoft and or hard tissues forming part of, or adjacent to, the treatedanatomical structures. For example, with regard to the PCL and/or theACL, an imaging test can be utilized to identify, for example, theorigin and/or the insertion of the PCL and the ACL on the femur andtibia. The origin and the insertion can be identified by visualizing,for example, the ligaments directly, as is possible with MRI or spiralCT arthrography, or by visualizing bony landmarks known to be the originor insertion of the ligament such as the medial and lateral tibialspines. Such structures can be subsequently modeled on a suitablecomputing system, or imaged directly from the structures, or acombination thereof.

An implant system and/or surgical tool can then be selected or designedbased on the image data so that, for example, the femoral componentpreserves the ACL and/or PCL origin, and the tibial component preservesthe ACL and/or PCL attachment. The implant can be selected or designedso that bone cuts adjacent to the ACL or PCL attachment or origin do notweaken the bone to induce a potential fracture. If desired, a motionstudy or other three-dimensional analysis can be conducted to determineif portions of the implant will directly or indirectly contact orotherwise influence (i.e., force other structures into contact with)surrounding soft or hard tissue structures. Similar studies can analyzethe implant and/or surrounding hard or soft tissues to determine what,if any, effects the implant will have on the surrounding tissues,including through the effect of the surgical procedure, e.g. cutting,drilling, burring, depth of cut, etc.

For ACL preservation, the implant can have two unicompartmental tibialcomponents that can be selected or designed and placed using the imagedata. Alternatively, the implant can have an anterior bridge component.The width of the anterior bridge in AP dimension, its thickness in thesuperoinferior dimension or its length in mediolateral dimension can beselected or designed using the imaging data and, specifically, the knowninsertion of the ACL and/or PCL.

As can be seen in FIGS. 60A and 60B, the posterior or any margin of animplant component, e.g. a polyethylene- or metal-backed tray withpolyethylene inserts, can be selected and/or designed using the imagingdata or shapes derived from the imaging data so that the implantcomponent includes one or more external anatomical relief surfaces 1300that desirably will not interfere with and stay clear of the PCL orother tendons such as the popliteus tendon. This can be achieved, forexample, by including external anatomical relief surfaces comprising oneor more concavities or removal of other structures in the outline of theimplant that are specifically designed or selected or adapted to avoidthe ligament insertion. In various other embodiments, an implant caninclude an external anatomical relief surface comprising one or moreprojections or other surfaces that contact, guide or otherwise influenceother tissues in some manner to prevent unwanted contact or otherinteraction with other portions of the implant (e.g., a projection couldact as a guide or other feature to prevent a tendon or other structurefrom being “pinched” and/or severed by interacting articulating surfacesof the implant and/or other surfaces of the implant and/or naturaljoint. Such external anatomical relief surfaces could prevent structuresfrom contacting moving portions of the implant, as well as prevent thestructures from moving into contact with surfaces that could sever,abrade and/or otherwise damage or injure the structures (either quicklyor after long-term repetitive contact).

If desired and/or as necessary, any implant component can be selectedand/or adapted to include external anatomical relief surfaces thatdesirably stay clear of important ligament structures. Imaging data canhelp identify or derive shape or location information on suchligamentous structures. For example, the lateral femoral condyle of aunicompartmental, bicompartmental or total knee system can include aconcavity or divot to avoid the popliteus tendon. Imaging data can beused to design a tibial component (all polyethylene or other plasticmaterial or metal backed) that avoids the attachment of the anteriorand/or posterior cruciate ligament; specifically, the contour of theimplant can be shaped so that it will stay clear of these ligamentousstructures. A safety margin, e.g. 2 mm or 3 mm or 5 mm or 7 mm or 10 mmcan be applied to the design of the edge of the component to allow thesurgeon more intraoperative flexibility. In a shoulder, the glenoidcomponent can include one or more external anatomical relief surfaces,such as concavities or divots, to avoid a subscapularis tendon or abiceps tendon or other tendons. In a hip, the femoral component caninclude an external anatomical relief surface selected or designed toavoid an iliopsoas or adductor tendon or other tendons.

With regards to a tibial tray component, various embodiments couldinclude external anatomical relief surface features to avoid undesirablecontact with surrounding ligaments and/or tendons, include (1) depth ofdish optionally adapted to presence or absence of intact anterior and/orposterior cruciate ligaments, and (2) depth of trough optionally adaptedto presence or absence of intact anterior and/or posterior cruciateligaments.

Additional tibial tray designs could include features to avoidadditional soft tissue structures including those disclosed in FIGS. 61ATHROUGH 61D. For example, FIG. 61C depicts a tibial tray and inserthaving an undesirable medial-lateral width that results in contact withthe medial-collateral ligament (MCL) on one side and the lateralcollateral ligament (LCL) on the other side of the tray/insert. Ifdesired, the tray and/or insert could include one or more indentationsor voids (not shown) on one or more sides that accommodate the MCLand/or LCL ligaments, allowing the knee to flex and extend without unduecontact and/or wear of the ligaments along the sides of the tray and/orinsert.

Alternatively, or in combination with one or more anatomical reliefsurfaces, indentations and/or voids, the tray and/or insert canincorporate one or more shape(s) that accommodate the various ligamentsof the knee and desirably avoid and/or reduce undesirable contact withsuch ligamentous structures, to include designs such as shown in dottedlines in FIGS. 61A and 61B as well as the design shown in 61D.

Example 8 Adjustable Contact Surfaces and Anatomical Relief Surfaces inSurgical Tools

FIGS. 62A through 62C depict a series of jigs designed to makepatient-specific cuts to the tibia. An exemplary tibial jig, depicted inFIG. 62A, is first placed on the anterior tibial cortex, with extendersonto the tibial plateau. The extenders can include cartilage or bonefacing surfaces that are patient specific. A Steinmann or other pin canbe placed in the medial and/or lateral tibial plateau through a hole inthe extender. The Steinmann pin can then be used as a guide for a toolused to core or surgically remove the cartilage surrounding the pin. Inthis manner, it is possible to design the extenders so that the patientspecific shape is derived from the subchondral bone rather than thecartilage, e.g. subchondral bone subjacent to cartilage, and so that theextender can rest on the subchondral bone after the coring procedure.This technique can be beneficial when various degrees of cartilage lossin one plateau or differences in cartilage loss between a medial plateauand a lateral plateau are not well visualized on a CT scan or MRI scan.

FIGS. 62A through 62C depict one embodiment of a surgical tool or jigthat incorporates adjustable contact surfaces that can be extendedand/or retracted to account for differing thicknesses of the articularcartilage including normal and diseased cartilage. In variousembodiments, the various contact surfaces can incorporate and/or beseparated by one or more anatomical relief surfaces.

Where the patient-specific imaging information has been collected usingx-rays and/or CT scans or the like (or where artifacts are adjacent toor in the line-of-sight of areas being imaged), it is often difficult(if not impossible) to visualize the articular cartilage and other softtissues, which potentially results in an unknown depth of cartilageduring the surgical procedure. In this embodiment, the subchondral bonecontact surfaces comprise an adjustable screw arrangement or otheradjustable mechanism, which can be advance and/or retracted as desired,to account for varying thickness of articular cartilage and/oraccommodate other variations or unknown quantities regarding theanatomical surfaces. One or more such screws or adjustment mechanismscan be advanced to equal depths, or can be asymmetric lengths, asdesired by the surgeon. Optionally, the screws can be printed during thegeneration of the disposable jig with a 3D printing process. In variousalternative embodiments, the patient-specific surgical tool can bedesigned to contain portions that rest on cartilage, other portions thatrest on bone (subchondral, cortical, trabecular, and/or variousanatomical relief surfaces as described herein). For example, a tool mayrest on the articular cartilage of a femoral condyle and also curvearound the condylar edges to contact bone. The surgical tool can alsoinclude anatomical relief surfaces that rest on or otherwise contact oraccommodate areas that include osteophytes, or that otherwise avoidcontact with various portions of the underlying anatomical surfaces.

In various embodiments, the patient's anatomical information for thesurgical tools may be derived using different 2D or 3D imagingtechniques. Since some imaging techniques do not display soft tissue,cartilage surface information may be estimated by offsetting theunderlying bone surface by the expected cartilage thickness. If asurgical tool is designed to rest on cartilage and on bone, anatomicalrelief surfaces (i.e., “offset” surfaces) and non-offset surfaces maydesirably be combined to design the patient-specific tool. This can beachieved by calculating smooth transitions between portions of offsetand non-offset surfaces. Alternatively, an offset surface may be used totrim a non-offset surface or vice versa.

Example 9 Anatomical Relief Surfaces in Surgical Tools for VariousAnatomy

If desired, one or more sets of jigs can be designed to includeanatomical relief surfaces that desirably facilitate and/or accommodatesurgical procedures on bones and joint other than the knee. Desirably,the surgical tools/jigs are designed in connection with the design of apatient-specific implant component. The designed jigs guide the surgeonin performing one or more patient-specific cuts to the bone so thatthose cut bone surface(s) negatively-match the patient-specific bonecuts of the implant component.

FIG. 63A depicts a normal humeral head and upper humerus which formspart of a shoulder joint. FIG. 63B depicts the humeral head having analignment jig designed to identify and located various portions of thehumeral anatomy. In this embodiment, a jig having a plurality ofconforming surfaces has been designed using patient-specific informationregarding one or more of the humerus, the humeral neck, the greatertuberosity and/or the lesser tuberosity of the humerus. Desirably, theconforming surfaces will fit onto the humerus on only one position andorientation, thereby aligning to the humerus in a known position. Thisembodiment can incorporate an alignment hole 18400 which aligns with anaxis 18410 of the humeral head. After proper positioning of the jig, apin or other mechanism (i.e., drill, reamer, etc.) can be inserted intothe hole 18400, and provide a secure reference point for varioussurgical operations, including the reaming of the humeral head and/ordrilling of the axis 18400 in preparation for a humeral head resurfacingimplant or other surgical procedure. The alignment mechanisms may beconnected to the one or more conforming surfaces by linkages (removable,moveable and/or fixed) or other devices, or the entire jig may be formedfrom a single piece and extend over a substantial portion of the humeralhead and/or other bone.

FIG. 63C depicts an alternative embodiment of a humeral head jig thatutilizes a single conforming surface to align the jig. In thisembodiment, the jib includes an anatomical relief surface that issubstantially a negative and engages one or more protrusions orosteophytes of the anatomical surface, which facilitates alignment andpositioning of the jig in a known manner.

FIG. 64A depicts a humeral head with osteophytes, and FIGS. 64B and 64Cdepict the humeral head with a more normalized surface that has beencorrected by virtual removal of the osteophytes. FIG. 65A depicts ahumeral head with voids, fissures or cysts, and FIGS. 65B and 65C depictthe humeral head with a more normalized surface that has been correctedby virtual removal of the voids, fissures or cysts. As previouslydisclosed, various embodiments of the surgical tools and/or implantsdescribed herein can incorporate anatomical relief surfaces that conformto, are substantially a negative, encompass, engulf or otherwise engageand/or avoid engagement of such anatomical features, which can includethe virtual and/or actual removal of some, but not all, of such surfacefeatures from the patient's anatomy prior to introduction of thesurgical tools and/or implant.

FIG. 66A depicts a glenoid component with osteophytes, and FIG. 66Bdepicts the glenoid component with a more normalized surface that hasbeen corrected by virtual removal of the osteophytes. FIGS. 66C and 66Ddepict two alternative embodiments of a glenoid jig for use with theglenoid, each of which incorporates conforming surfaces with anatomicalrelief surfaces that accommodate the osteophytes. If desired, the jig ofFIG. 66C can be formed from an elastic or flexible material to allow itto “snap fit” over the glenoid component and associated osteophytes. Aspreviously noted, the jigs can include various alignment holes, slots,etc., to allow placement of pins or other surgical actions.

FIG. 67A depicts a glenoid component with voids, fissures or cysts, andFIG. 67B depicts the glenoid component with a more normalized surfacethat has been corrected by virtual “filling” of the voids, fissures orcysts. FIG. 67C depicts an embodiment of a glenoid jig for use with theglenoid component, which incorporates various conforming surfaces withanatomical relief surfaces that accommodate the voids, fissures and/orcysts (and other surfaces) of the glenoid component.

The foregoing description of embodiments have been provided for thepurposes of illustration and description. It is not intended to beexhaustive or to be limited to the precise forms disclosed. Manymodifications and variations will be apparent to the practitionerskilled in the art. The embodiments were chosen and described in orderto best explain the principles and their practical applications, therebyenabling others skilled in the art to understand the disclosure and thevarious embodiments and with various modifications that are suited tothe particular use contemplated. It is intended that the scope bedefined by the following claims equivalents thereof.

1. A surgical assistance tool for joint arthroplasty, the surgicalassistance tool comprising: a first template, the first templateincluding: at least one surface for engaging at least a portion of atrochlear region of a knee joint, the surface being substantially anegative of one or more portions of the trochlear region; at least onerelieved portion of the surface, the relieved portion being relievedrelative to a corresponding sub-portion of the trochlear region suchthat the relieved portion does not engage the corresponding portion ofthe trochlear region when the surface is engaged with the portion of thetrochlear region; and at least one guide for directing movement of asurgical instrument; and wherein said guide has a predeterminedorientation relative to one of an anatomical and a biomechanical axis.2. The surgical assistance tool of claim 1, wherein said relievedportion corresponds to portions of a trochlear groove.
 3. The surgicalassistance tool of claim 1, wherein the at least one guide is one of aguide aperture, a reaming aperture, a drill aperture and a cut plane. 4.The surgical assistance tool of claim 1, further comprising anadjustment mechanism for adjusting a position of the at least one guiderelative to the at least one surface.
 5. The surgical assistance tool ofclaim 1, further comprising an adjustment mechanism for adjusting anorientation of the at least one guide relative to the at least onesurface.
 6. The surgical assistance tool of claim 1, wherein the surfaceis substantially a negative of a portion of an articular cartilagesurface of the trochlear region.
 7. The surgical assistance tool ofclaim 1, wherein the surface is substantially a negative of a portion ofa subchondral bone surface of the trochlear region.
 8. The surgicalassistance tool of claim 1, wherein the at least one surface comprises aplurality of anatomical relief surfaces.
 9. The surgical assistance toolof claim 1, wherein the at least one surface comprises a plurality ofsurfaces for engaging at least a portion of the trochlear region of theknee joint.
 10. The surgical assistance tool of claim 1, wherein saidanatomic relief accommodates one or more osteophytes on the trochlearregion of the knee joint.
 11. The surgical assistance tool of claim 1,wherein said anatomic relief accommodates an area of normal cartilage onthe trochlear region of the knee joint.
 12. The surgical assistance toolof claim 1, wherein said anatomic relief accommodates an area ofdiseased cartilage on the trochlear region of the knee joint.
 13. Thesurgical assistance tool of claim 1, wherein said anatomic reliefaccommodates an area of normal and diseased cartilage on the trochlearregion of the knee joint.
 14. The surgical assistance tool of claim 1,wherein said anatomic relief accommodates an area of subchondral bone onthe trochlear region of the knee joint.
 15. A system for jointarthroplasty, the system comprising: a first template, the firsttemplate including: at least one surface for engaging a first articularsurface of a joint, the surface being substantially a negative ofportions or all of the first articular surface; at least a portion ofthe surface further including an anatomical relief; and at least oneguide for directing movement of a surgical instrument; and wherein saidguide has a predetermined orientation relative to one of an anatomicaland a biomechanical axis.
 16. The system of claim 15, wherein the atleast one guide is one of a guide aperture, a reaming aperture, a drillaperture and a cut plane.
 17. The system of claim 15, further comprisingan adjustment mechanism for adjusting a position of the at least oneguide relative to the at least one surface.
 18. The system of claim 15,further comprising an adjustment mechanism for adjusting an orientationof the at least one guide relative to the at least one surface.
 19. Thesystem of claim 15, wherein said anatomic relief accommodates one ormore osteophytes on the surface of the joint.
 20. The system of claim15, wherein said anatomic relief accommodates an area of normalcartilage on the surface of the joint.
 21. The system of claim 15,wherein said anatomic relief accommodates an area of diseased cartilageon the surface of the joint.
 22. The system of claim 15, wherein saidanatomic relief accommodates an area of normal and diseased cartilage onthe surface of the joint.
 23. The system of claim 15, wherein saidanatomic relief accommodates an area of subchondral bone on the surfaceof the joint.
 24. A method of making a surgical tool, the methodcomprising: obtaining image data associated with at least a portion of ajoint; deriving joint surface information from the image data;determining at least a portion of the joint surface to be engaged by acontact surface; determining an anatomical structure to be disengagedfrom a corresponding anatomical relief surface, and providing a surgicaltool that includes a guide, the contact surface and the anatomicalrelief surface, the contact surface for engaging at least a portion ofthe joint surface, the anatomical relief surface being substantiallydisengaged from the anatomical structure when the contact surface isengaged with the at least a portion of the joint surface.
 25. The methodaccording to claim 24, wherein the anatomical relief surface is adjacentto the contact surface.
 26. The method according to claim 24, wherein anentirety of a perimeter of the anatomical relief surface is adjacent tothe contact surface.
 27. The method according to claim 24, wherein aportion of a perimeter of the anatomical relief surface is adjacent tothe contact surface.
 28. The method according to claim 24, wherein theanatomical relief surface is not adjacent to the contact surface. 29.The method of claim 24, further comprising: engaging the contact surfaceof the surgical tool with the joint surface associated with the joint;and directing movement of the surgical instrument in preparing animplant site using the at least one guide.
 30. The method according toclaim 24, wherein the at least one guide is one of a guide aperture, areaming aperture, a drill aperture and a cut plane.
 31. The methodaccording to claim 24, wherein the guide directs the surgical instrumentin making a bone cut at a predetermined distance from a surface of thejoint.
 32. The method according to claim 24, wherein the guide directsthe surgical instrument in making a planar bone cut in the joint. 33.The method according to claim 24, further comprising determining, fromsaid image data, the desired orientation of the implant in relation toat least one of an anatomic landmark, an anatomic axis, and abiomechanical axis associated with the joint.
 34. The method accordingto claim 24, wherein the derived joint surface comprises subchondralbone of the joint.
 35. The method according to claim 24, wherein thederived joint surface comprises articular cartilage of the joint. 36.The method according to claim 24, wherein the surgical tool furthercomprises a plurality of anatomical relief surfaces.
 37. The methodaccording to claim 24, wherein said anatomic relief accommodates one ormore osteophytes on the at least a portion of the joint surface.
 38. Themethod according to claim 24, wherein said anatomic relief accommodatesan area of normal cartilage on the at least a portion of the jointsurface.
 39. The method according to claim 24, wherein said anatomicrelief accommodates an area of diseased cartilage on the at least aportion of the joint surface.
 40. The method according to claim 24,wherein said anatomic relief accommodates an area of normal and diseasedcartilage on the at least a portion of the joint surface.
 41. The methodaccording to claim 24, wherein said anatomic relief accommodates an areaof subchondral bone on the at least a portion of the joint surface. 42.A surgical assistance tool for joint arthroplasty, the surgicalassistance tool comprising: a first template, the first templateincluding: at least one surface for engaging at least a portion of atrochlear region of a knee joint, the surface being substantially anegative of one or more portions of the trochlear cartilage; at least aportion of the surface further including an anatomical relief; and atleast one guide for directing movement of a surgical instrument.
 43. Thesurgical assistance tool of claim 42, wherein said anatomic reliefaccommodates one or more osteophytes on the trochlear region of the kneejoint.
 44. The surgical assistance tool of claim 42, wherein saidanatomic relief accommodates an area of normal cartilage on thetrochlear region of the knee joint.
 45. The surgical assistance tool ofclaim 42, wherein said anatomic relief accommodates an area of diseasedcartilage on the trochlear region of the knee joint.
 46. The surgicalassistance tool of claim 42, wherein said anatomic relief accommodatesan area of normal and diseased cartilage on the trochlear region of theknee joint.
 47. The surgical assistance tool of claim 42, wherein saidanatomic relief accommodates an area of subchondral bone on thetrochlear region of the knee joint.
 48. A system for joint arthroplasty,the system comprising: a first template, the first template including:at least one surface for engaging a first cartilage surface of a joint,the surface being substantially a negative of portions of the firstcartilage surface; at least a portion of the surface further includingan anatomical relief; and at least one guide for directing movement of asurgical instrument; and wherein said guide has a predeterminedorientation relative to one of an anatomical and a biomechanical axis.49. The system of claim 48, wherein said anatomic relief accommodatesone or more osteophytes of the joint.
 50. The system of claim 48,wherein said anatomic relief accommodates an area of normal cartilage ofthe joint.
 51. The system of claim 48, wherein said anatomic reliefaccommodates an area of diseased cartilage of the joint.
 52. The systemof claim 48, wherein said anatomic relief accommodates an area of normaland diseased cartilage of the joint.
 53. The system of claim 48, whereinsaid anatomic relief accommodates an area of subchondral bone of thejoint.
 54. The method according to claim 24, wherein providing thesurgical tool includes: shaping the contact surface based on the derivedjoint surface information such that the contact surface is substantiallya negative of the derived joint surface; and determining position, shapeand/or orientation of the at least one guide from the image data, suchthat changes induced on the implant site by the surgical instrumentensures a desired orientation of an implant
 55. The method according toclaim 24, wherein the anatomical structure is an uncut surface portionof the joint.
 56. The method according to claim 24, wherein theanatomical structure is a cut surface portion of the joint.
 57. Themethod according to claim 24, wherein the anatomical structure is atrochlear groove.
 58. The method according to claim 24, wherein theanatomical structure is an osteophyte.